diff --git a/src/Symfony/Bridge/Twig/Command/DebugCommand.php b/src/Symfony/Bridge/Twig/Command/DebugCommand.php
index 37a37786db..ed1d63fd86 100644
--- a/src/Symfony/Bridge/Twig/Command/DebugCommand.php
+++ b/src/Symfony/Bridge/Twig/Command/DebugCommand.php
@@ -26,6 +26,8 @@ use Twig\Environment;
  */
 class DebugCommand extends Command
 {
+    protected static $defaultName = 'debug:twig';
+
     private $twig;
 
     public function __construct(Environment $twig)
@@ -38,7 +40,6 @@ class DebugCommand extends Command
     protected function configure()
     {
         $this
-            ->setName('debug:twig')
             ->setDefinition(array(
                 new InputArgument('filter', InputArgument::OPTIONAL, 'Show details for all entries matching this filter'),
                 new InputOption('format', null, InputOption::VALUE_REQUIRED, 'The output format (text or json)', 'text'),
diff --git a/src/Symfony/Bridge/Twig/Command/LintCommand.php b/src/Symfony/Bridge/Twig/Command/LintCommand.php
index 2973f6b4de..7a707ad0b1 100644
--- a/src/Symfony/Bridge/Twig/Command/LintCommand.php
+++ b/src/Symfony/Bridge/Twig/Command/LintCommand.php
@@ -31,6 +31,8 @@ use Twig\Source;
  */
 class LintCommand extends Command
 {
+    protected static $defaultName = 'lint:twig';
+
     private $twig;
 
     public function __construct(Environment $twig)
@@ -43,7 +45,6 @@ class LintCommand extends Command
     protected function configure()
     {
         $this
-            ->setName('lint:twig')
             ->setDescription('Lints a template and outputs encountered errors')
             ->addOption('format', null, InputOption::VALUE_REQUIRED, 'The output format', 'txt')
             ->addArgument('filename', InputArgument::IS_ARRAY)
diff --git a/src/Symfony/Bridge/Twig/composer.json b/src/Symfony/Bridge/Twig/composer.json
index 8463d20d52..4593db62ed 100644
--- a/src/Symfony/Bridge/Twig/composer.json
+++ b/src/Symfony/Bridge/Twig/composer.json
@@ -39,7 +39,8 @@
         "symfony/web-link": "~3.4|~4.0"
     },
     "conflict": {
-        "symfony/form": "<3.4"
+        "symfony/form": "<3.4",
+        "symfony/console": "<3.4"
     },
     "suggest": {
         "symfony/finder": "",
diff --git a/src/Symfony/Bundle/FrameworkBundle/Command/AboutCommand.php b/src/Symfony/Bundle/FrameworkBundle/Command/AboutCommand.php
index e4852da379..1006943a23 100644
--- a/src/Symfony/Bundle/FrameworkBundle/Command/AboutCommand.php
+++ b/src/Symfony/Bundle/FrameworkBundle/Command/AboutCommand.php
@@ -29,15 +29,14 @@ use Symfony\Component\HttpKernel\KernelInterface;
  */
 class AboutCommand extends Command
 {
+    protected static $defaultName = 'about';
+
     /**
      * {@inheritdoc}
      */
     protected function configure()
     {
-        $this
-            ->setName('about')
-            ->setDescription('Displays information about the current project')
-        ;
+        $this->setDescription('Displays information about the current project');
     }
 
     /**
diff --git a/src/Symfony/Bundle/FrameworkBundle/Command/AssetsInstallCommand.php b/src/Symfony/Bundle/FrameworkBundle/Command/AssetsInstallCommand.php
index d314748670..c9b37daa7d 100644
--- a/src/Symfony/Bundle/FrameworkBundle/Command/AssetsInstallCommand.php
+++ b/src/Symfony/Bundle/FrameworkBundle/Command/AssetsInstallCommand.php
@@ -36,6 +36,8 @@ class AssetsInstallCommand extends Command
     const METHOD_ABSOLUTE_SYMLINK = 'absolute symlink';
     const METHOD_RELATIVE_SYMLINK = 'relative symlink';
 
+    protected static $defaultName = 'assets:install';
+
     private $filesystem;
 
     public function __construct(Filesystem $filesystem)
@@ -51,7 +53,6 @@ class AssetsInstallCommand extends Command
     protected function configure()
     {
         $this
-            ->setName('assets:install')
             ->setDefinition(array(
                 new InputArgument('target', InputArgument::OPTIONAL, 'The target directory', 'public'),
             ))
diff --git a/src/Symfony/Bundle/FrameworkBundle/Command/CacheClearCommand.php b/src/Symfony/Bundle/FrameworkBundle/Command/CacheClearCommand.php
index 1cf530ceba..1bb9c4c530 100644
--- a/src/Symfony/Bundle/FrameworkBundle/Command/CacheClearCommand.php
+++ b/src/Symfony/Bundle/FrameworkBundle/Command/CacheClearCommand.php
@@ -32,6 +32,8 @@ use Symfony\Component\Finder\Finder;
  */
 class CacheClearCommand extends Command
 {
+    protected static $defaultName = 'cache:clear';
+
     private $cacheClearer;
     private $filesystem;
 
@@ -53,7 +55,6 @@ class CacheClearCommand extends Command
     protected function configure()
     {
         $this
-            ->setName('cache:clear')
             ->setDefinition(array(
                 new InputOption('no-warmup', '', InputOption::VALUE_NONE, 'Do not warm up the cache'),
                 new InputOption('no-optional-warmers', '', InputOption::VALUE_NONE, 'Skip optional cache warmers (faster)'),
diff --git a/src/Symfony/Bundle/FrameworkBundle/Command/CachePoolClearCommand.php b/src/Symfony/Bundle/FrameworkBundle/Command/CachePoolClearCommand.php
index 2bd42e69ec..aa17ad3a39 100644
--- a/src/Symfony/Bundle/FrameworkBundle/Command/CachePoolClearCommand.php
+++ b/src/Symfony/Bundle/FrameworkBundle/Command/CachePoolClearCommand.php
@@ -26,6 +26,8 @@ use Symfony\Component\HttpKernel\CacheClearer\Psr6CacheClearer;
  */
 final class CachePoolClearCommand extends Command
 {
+    protected static $defaultName = 'cache:pool:clear';
+
     private $poolClearer;
 
     public function __construct(Psr6CacheClearer $poolClearer)
@@ -41,7 +43,6 @@ final class CachePoolClearCommand extends Command
     protected function configure()
     {
         $this
-            ->setName('cache:pool:clear')
             ->setDefinition(array(
                 new InputArgument('pools', InputArgument::IS_ARRAY | InputArgument::REQUIRED, 'A list of cache pools or cache pool clearers'),
             ))
diff --git a/src/Symfony/Bundle/FrameworkBundle/Command/CachePoolPruneCommand.php b/src/Symfony/Bundle/FrameworkBundle/Command/CachePoolPruneCommand.php
index 741979bd4f..1c9cef9b93 100644
--- a/src/Symfony/Bundle/FrameworkBundle/Command/CachePoolPruneCommand.php
+++ b/src/Symfony/Bundle/FrameworkBundle/Command/CachePoolPruneCommand.php
@@ -24,6 +24,8 @@ use Symfony\Component\Console\Style\SymfonyStyle;
  */
 final class CachePoolPruneCommand extends Command
 {
+    protected static $defaultName = 'cache:pool:prune';
+
     private $pools;
 
     /**
@@ -42,7 +44,6 @@ final class CachePoolPruneCommand extends Command
     protected function configure()
     {
         $this
-            ->setName('cache:pool:prune')
             ->setDescription('Prune cache pools')
             ->setHelp(<<<'EOF'
 The <info>%command.name%</info> command deletes all expired items from all pruneable pools.
diff --git a/src/Symfony/Bundle/FrameworkBundle/Command/CacheWarmupCommand.php b/src/Symfony/Bundle/FrameworkBundle/Command/CacheWarmupCommand.php
index b890ce8c3f..5219e1dbba 100644
--- a/src/Symfony/Bundle/FrameworkBundle/Command/CacheWarmupCommand.php
+++ b/src/Symfony/Bundle/FrameworkBundle/Command/CacheWarmupCommand.php
@@ -27,6 +27,8 @@ use Symfony\Component\HttpKernel\CacheWarmer\CacheWarmerAggregate;
  */
 class CacheWarmupCommand extends Command
 {
+    protected static $defaultName = 'cache:warmup';
+
     private $cacheWarmer;
 
     public function __construct(CacheWarmerAggregate $cacheWarmer)
@@ -42,7 +44,6 @@ class CacheWarmupCommand extends Command
     protected function configure()
     {
         $this
-            ->setName('cache:warmup')
             ->setDefinition(array(
                 new InputOption('no-optional-warmers', '', InputOption::VALUE_NONE, 'Skip optional cache warmers (faster)'),
             ))
diff --git a/src/Symfony/Bundle/FrameworkBundle/Command/ConfigDebugCommand.php b/src/Symfony/Bundle/FrameworkBundle/Command/ConfigDebugCommand.php
index f460fd5f09..5a55332b33 100644
--- a/src/Symfony/Bundle/FrameworkBundle/Command/ConfigDebugCommand.php
+++ b/src/Symfony/Bundle/FrameworkBundle/Command/ConfigDebugCommand.php
@@ -28,13 +28,14 @@ use Symfony\Component\Yaml\Yaml;
  */
 class ConfigDebugCommand extends AbstractConfigCommand
 {
+    protected static $defaultName = 'debug:config';
+
     /**
      * {@inheritdoc}
      */
     protected function configure()
     {
         $this
-            ->setName('debug:config')
             ->setDefinition(array(
                 new InputArgument('name', InputArgument::OPTIONAL, 'The bundle name or the extension alias'),
                 new InputArgument('path', InputArgument::OPTIONAL, 'The configuration option path'),
diff --git a/src/Symfony/Bundle/FrameworkBundle/Command/ConfigDumpReferenceCommand.php b/src/Symfony/Bundle/FrameworkBundle/Command/ConfigDumpReferenceCommand.php
index fb51f8c3fc..62bdfec8c9 100644
--- a/src/Symfony/Bundle/FrameworkBundle/Command/ConfigDumpReferenceCommand.php
+++ b/src/Symfony/Bundle/FrameworkBundle/Command/ConfigDumpReferenceCommand.php
@@ -30,13 +30,14 @@ use Symfony\Component\Console\Style\SymfonyStyle;
  */
 class ConfigDumpReferenceCommand extends AbstractConfigCommand
 {
+    protected static $defaultName = 'config:dump-reference';
+
     /**
      * {@inheritdoc}
      */
     protected function configure()
     {
         $this
-            ->setName('config:dump-reference')
             ->setDefinition(array(
                 new InputArgument('name', InputArgument::OPTIONAL, 'The Bundle name or the extension alias'),
                 new InputArgument('path', InputArgument::OPTIONAL, 'The configuration option path'),
diff --git a/src/Symfony/Bundle/FrameworkBundle/Command/ContainerDebugCommand.php b/src/Symfony/Bundle/FrameworkBundle/Command/ContainerDebugCommand.php
index 6ec4f4b8c4..cbf9e8bdb6 100644
--- a/src/Symfony/Bundle/FrameworkBundle/Command/ContainerDebugCommand.php
+++ b/src/Symfony/Bundle/FrameworkBundle/Command/ContainerDebugCommand.php
@@ -33,6 +33,8 @@ use Symfony\Component\Config\FileLocator;
  */
 class ContainerDebugCommand extends Command
 {
+    protected static $defaultName = 'debug:container';
+
     /**
      * @var ContainerBuilder|null
      */
@@ -44,7 +46,6 @@ class ContainerDebugCommand extends Command
     protected function configure()
     {
         $this
-            ->setName('debug:container')
             ->setDefinition(array(
                 new InputArgument('name', InputArgument::OPTIONAL, 'A service name (foo)'),
                 new InputOption('show-private', null, InputOption::VALUE_NONE, 'Used to show public *and* private services'),
diff --git a/src/Symfony/Bundle/FrameworkBundle/Command/EventDispatcherDebugCommand.php b/src/Symfony/Bundle/FrameworkBundle/Command/EventDispatcherDebugCommand.php
index 69144d300e..75d9880798 100644
--- a/src/Symfony/Bundle/FrameworkBundle/Command/EventDispatcherDebugCommand.php
+++ b/src/Symfony/Bundle/FrameworkBundle/Command/EventDispatcherDebugCommand.php
@@ -29,6 +29,7 @@ use Symfony\Component\EventDispatcher\EventDispatcherInterface;
  */
 class EventDispatcherDebugCommand extends Command
 {
+    protected static $defaultName = 'debug:event-dispatcher';
     private $dispatcher;
 
     public function __construct(EventDispatcherInterface $dispatcher)
@@ -44,7 +45,6 @@ class EventDispatcherDebugCommand extends Command
     protected function configure()
     {
         $this
-            ->setName('debug:event-dispatcher')
             ->setDefinition(array(
                 new InputArgument('event', InputArgument::OPTIONAL, 'An event name'),
                 new InputOption('format', null, InputOption::VALUE_REQUIRED, 'The output format  (txt, xml, json, or md)', 'txt'),
diff --git a/src/Symfony/Bundle/FrameworkBundle/Command/RouterDebugCommand.php b/src/Symfony/Bundle/FrameworkBundle/Command/RouterDebugCommand.php
index 61345c0c49..425f607f84 100644
--- a/src/Symfony/Bundle/FrameworkBundle/Command/RouterDebugCommand.php
+++ b/src/Symfony/Bundle/FrameworkBundle/Command/RouterDebugCommand.php
@@ -33,6 +33,7 @@ use Symfony\Component\Routing\Route;
  */
 class RouterDebugCommand extends Command
 {
+    protected static $defaultName = 'debug:router';
     private $router;
 
     public function __construct(RouterInterface $router)
@@ -48,7 +49,6 @@ class RouterDebugCommand extends Command
     protected function configure()
     {
         $this
-            ->setName('debug:router')
             ->setDefinition(array(
                 new InputArgument('name', InputArgument::OPTIONAL, 'A route name'),
                 new InputOption('show-controllers', null, InputOption::VALUE_NONE, 'Show assigned controllers in overview'),
diff --git a/src/Symfony/Bundle/FrameworkBundle/Command/RouterMatchCommand.php b/src/Symfony/Bundle/FrameworkBundle/Command/RouterMatchCommand.php
index 4c99b9dbe5..74ef9fdc96 100644
--- a/src/Symfony/Bundle/FrameworkBundle/Command/RouterMatchCommand.php
+++ b/src/Symfony/Bundle/FrameworkBundle/Command/RouterMatchCommand.php
@@ -30,6 +30,8 @@ use Symfony\Component\Routing\Matcher\TraceableUrlMatcher;
  */
 class RouterMatchCommand extends Command
 {
+    protected static $defaultName = 'router:match';
+
     private $router;
 
     public function __construct(RouterInterface $router)
@@ -45,7 +47,6 @@ class RouterMatchCommand extends Command
     protected function configure()
     {
         $this
-            ->setName('router:match')
             ->setDefinition(array(
                 new InputArgument('path_info', InputArgument::REQUIRED, 'A path info'),
                 new InputOption('method', null, InputOption::VALUE_REQUIRED, 'Sets the HTTP method'),
diff --git a/src/Symfony/Bundle/FrameworkBundle/Command/TranslationDebugCommand.php b/src/Symfony/Bundle/FrameworkBundle/Command/TranslationDebugCommand.php
index 933a60a2d0..43a190a3be 100644
--- a/src/Symfony/Bundle/FrameworkBundle/Command/TranslationDebugCommand.php
+++ b/src/Symfony/Bundle/FrameworkBundle/Command/TranslationDebugCommand.php
@@ -41,6 +41,8 @@ class TranslationDebugCommand extends Command
     const MESSAGE_UNUSED = 1;
     const MESSAGE_EQUALS_FALLBACK = 2;
 
+    protected static $defaultName = 'debug:translation';
+
     private $translator;
     private $loader;
     private $extractor;
@@ -60,7 +62,6 @@ class TranslationDebugCommand extends Command
     protected function configure()
     {
         $this
-            ->setName('debug:translation')
             ->setDefinition(array(
                 new InputArgument('locale', InputArgument::REQUIRED, 'The locale'),
                 new InputArgument('bundle', InputArgument::OPTIONAL, 'The bundle name or directory where to load the messages, defaults to app/Resources folder'),
diff --git a/src/Symfony/Bundle/FrameworkBundle/Command/TranslationUpdateCommand.php b/src/Symfony/Bundle/FrameworkBundle/Command/TranslationUpdateCommand.php
index b6427b3b68..fca86f92a4 100644
--- a/src/Symfony/Bundle/FrameworkBundle/Command/TranslationUpdateCommand.php
+++ b/src/Symfony/Bundle/FrameworkBundle/Command/TranslationUpdateCommand.php
@@ -34,6 +34,8 @@ use Symfony\Component\Translation\Writer\TranslationWriterInterface;
  */
 class TranslationUpdateCommand extends Command
 {
+    protected static $defaultName = 'translation:update';
+
     private $writer;
     private $loader;
     private $extractor;
@@ -61,7 +63,6 @@ class TranslationUpdateCommand extends Command
     protected function configure()
     {
         $this
-            ->setName('translation:update')
             ->setDefinition(array(
                 new InputArgument('locale', InputArgument::REQUIRED, 'The locale'),
                 new InputArgument('bundle', InputArgument::OPTIONAL, 'The bundle name or directory where to load the messages, defaults to app/Resources folder'),
diff --git a/src/Symfony/Bundle/FrameworkBundle/Command/WorkflowDumpCommand.php b/src/Symfony/Bundle/FrameworkBundle/Command/WorkflowDumpCommand.php
index e06547103d..1c031f5999 100644
--- a/src/Symfony/Bundle/FrameworkBundle/Command/WorkflowDumpCommand.php
+++ b/src/Symfony/Bundle/FrameworkBundle/Command/WorkflowDumpCommand.php
@@ -26,13 +26,14 @@ use Symfony\Component\Workflow\Marking;
  */
 class WorkflowDumpCommand extends Command
 {
+    protected static $defaultName = 'workflow:dump';
+
     /**
      * {@inheritdoc}
      */
     protected function configure()
     {
         $this
-            ->setName('workflow:dump')
             ->setDefinition(array(
                 new InputArgument('name', InputArgument::REQUIRED, 'A workflow name'),
                 new InputArgument('marking', InputArgument::IS_ARRAY, 'A marking (a list of places)'),
diff --git a/src/Symfony/Bundle/FrameworkBundle/Command/XliffLintCommand.php b/src/Symfony/Bundle/FrameworkBundle/Command/XliffLintCommand.php
index 354d714694..42ee30e145 100644
--- a/src/Symfony/Bundle/FrameworkBundle/Command/XliffLintCommand.php
+++ b/src/Symfony/Bundle/FrameworkBundle/Command/XliffLintCommand.php
@@ -24,6 +24,8 @@ use Symfony\Component\Translation\Command\XliffLintCommand as BaseLintCommand;
  */
 class XliffLintCommand extends BaseLintCommand
 {
+    protected static $defaultName = 'lint:xliff';
+
     public function __construct()
     {
         $directoryIteratorProvider = function ($directory, $default) {
diff --git a/src/Symfony/Bundle/FrameworkBundle/Command/YamlLintCommand.php b/src/Symfony/Bundle/FrameworkBundle/Command/YamlLintCommand.php
index 267a57027e..4edd92ff69 100644
--- a/src/Symfony/Bundle/FrameworkBundle/Command/YamlLintCommand.php
+++ b/src/Symfony/Bundle/FrameworkBundle/Command/YamlLintCommand.php
@@ -23,6 +23,8 @@ use Symfony\Component\Yaml\Command\LintCommand as BaseLintCommand;
  */
 class YamlLintCommand extends BaseLintCommand
 {
+    protected static $defaultName = 'lint:yaml';
+
     public function __construct()
     {
         $directoryIteratorProvider = function ($directory, $default) {
diff --git a/src/Symfony/Bundle/SecurityBundle/Command/InitAclCommand.php b/src/Symfony/Bundle/SecurityBundle/Command/InitAclCommand.php
index d79176001a..f242bb5780 100644
--- a/src/Symfony/Bundle/SecurityBundle/Command/InitAclCommand.php
+++ b/src/Symfony/Bundle/SecurityBundle/Command/InitAclCommand.php
@@ -27,6 +27,8 @@ use Doctrine\DBAL\Schema\SchemaException;
  */
 class InitAclCommand extends Command
 {
+    protected static $defaultName = 'init:acl';
+
     private $connection;
     private $schema;
 
@@ -44,7 +46,6 @@ class InitAclCommand extends Command
     protected function configure()
     {
         $this
-            ->setName('init:acl')
             ->setDescription('Mounts ACL tables in the database')
             ->setHelp(<<<'EOF'
 The <info>%command.name%</info> command mounts ACL tables in the database.
diff --git a/src/Symfony/Bundle/SecurityBundle/Command/SetAclCommand.php b/src/Symfony/Bundle/SecurityBundle/Command/SetAclCommand.php
index 59ecd6b0a0..e815174df0 100644
--- a/src/Symfony/Bundle/SecurityBundle/Command/SetAclCommand.php
+++ b/src/Symfony/Bundle/SecurityBundle/Command/SetAclCommand.php
@@ -32,6 +32,8 @@ use Symfony\Component\Security\Acl\Model\MutableAclProviderInterface;
  */
 class SetAclCommand extends Command
 {
+    protected static $defaultName = 'acl:set';
+
     private $provider;
 
     public function __construct(MutableAclProviderInterface $provider)
@@ -47,7 +49,6 @@ class SetAclCommand extends Command
     protected function configure()
     {
         $this
-            ->setName('acl:set')
             ->setDescription('Sets ACL for objects')
             ->setHelp(<<<EOF
 The <info>%command.name%</info> command sets ACL.
diff --git a/src/Symfony/Bundle/SecurityBundle/Command/UserPasswordEncoderCommand.php b/src/Symfony/Bundle/SecurityBundle/Command/UserPasswordEncoderCommand.php
index af6c866551..9a8c7f230a 100644
--- a/src/Symfony/Bundle/SecurityBundle/Command/UserPasswordEncoderCommand.php
+++ b/src/Symfony/Bundle/SecurityBundle/Command/UserPasswordEncoderCommand.php
@@ -31,6 +31,8 @@ use Symfony\Component\Security\Core\Encoder\EncoderFactoryInterface;
  */
 class UserPasswordEncoderCommand extends Command
 {
+    protected static $defaultName = 'security:encode-password';
+
     private $encoderFactory;
     private $userClasses;
 
@@ -48,7 +50,6 @@ class UserPasswordEncoderCommand extends Command
     protected function configure()
     {
         $this
-            ->setName('security:encode-password')
             ->setDescription('Encodes a password.')
             ->addArgument('password', InputArgument::OPTIONAL, 'The plain password to encode.')
             ->addArgument('user-class', InputArgument::OPTIONAL, 'The User entity class path associated with the encoder used to encode the password.')
diff --git a/src/Symfony/Bundle/SecurityBundle/Tests/Functional/SetAclCommandTest.php b/src/Symfony/Bundle/SecurityBundle/Tests/Functional/SetAclCommandTest.php
index 37cbffd9be..dbc9821b14 100644
--- a/src/Symfony/Bundle/SecurityBundle/Tests/Functional/SetAclCommandTest.php
+++ b/src/Symfony/Bundle/SecurityBundle/Tests/Functional/SetAclCommandTest.php
@@ -20,7 +20,6 @@ namespace Symfony\Bundle\SecurityBundle\Tests\Functional;
  * file that was distributed with this source code.
  */
 use Symfony\Bundle\FrameworkBundle\Console\Application;
-use Symfony\Bundle\SecurityBundle\Command\InitAclCommand;
 use Symfony\Bundle\SecurityBundle\Command\SetAclCommand;
 use Symfony\Component\Console\Tester\CommandTester;
 use Symfony\Component\Security\Acl\Domain\ObjectIdentity;
@@ -170,7 +169,6 @@ class SetAclCommandTest extends WebTestCase
         $kernel->boot();
 
         $application = new Application($kernel);
-        $application->add(new InitAclCommand($kernel->getContainer()->get('security.acl.dbal.connection'), $kernel->getContainer()->get('security.acl.dbal.schema')));
 
         $initAclCommand = $application->find('init:acl');
         $initAclCommandTester = new CommandTester($initAclCommand);
diff --git a/src/Symfony/Bundle/SecurityBundle/composer.json b/src/Symfony/Bundle/SecurityBundle/composer.json
index a0ac75fd80..b0ad7066e2 100644
--- a/src/Symfony/Bundle/SecurityBundle/composer.json
+++ b/src/Symfony/Bundle/SecurityBundle/composer.json
@@ -46,7 +46,8 @@
     },
     "conflict": {
         "symfony/var-dumper": "<3.4",
-        "symfony/event-dispatcher": "<3.4"
+        "symfony/event-dispatcher": "<3.4",
+        "symfony/console": "<3.4"
     },
     "suggest": {
         "symfony/security-acl": "For using the ACL functionality of this bundle"
diff --git a/src/Symfony/Bundle/TwigBundle/Resources/views/base_js.html.twig b/src/Symfony/Bundle/TwigBundle/Resources/views/base_js.html.twig
index 036af2b025..c18dd554dd 100644
--- a/src/Symfony/Bundle/TwigBundle/Resources/views/base_js.html.twig
+++ b/src/Symfony/Bundle/TwigBundle/Resources/views/base_js.html.twig
@@ -24,7 +24,7 @@
 
         var noop = function() {};
 
-        var profilerStorageKey = 'sf2/profiler/';
+        var profilerStorageKey = 'symfony/profiler/';
 
         var request = function(url, onSuccess, onError, payload, options) {
             var xhr = window.XMLHttpRequest ? new XMLHttpRequest() : new ActiveXObject('Microsoft.XMLHTTP');
diff --git a/src/Symfony/Bundle/WebProfilerBundle/Resources/views/Profiler/base_js.html.twig b/src/Symfony/Bundle/WebProfilerBundle/Resources/views/Profiler/base_js.html.twig
index b5f08f8691..4196196593 100644
--- a/src/Symfony/Bundle/WebProfilerBundle/Resources/views/Profiler/base_js.html.twig
+++ b/src/Symfony/Bundle/WebProfilerBundle/Resources/views/Profiler/base_js.html.twig
@@ -24,7 +24,7 @@
 
         var noop = function() {};
 
-        var profilerStorageKey = 'sf2/profiler/';
+        var profilerStorageKey = 'symfony/profiler/';
 
         var request = function(url, onSuccess, onError, payload, options) {
             var xhr = window.XMLHttpRequest ? new XMLHttpRequest() : new ActiveXObject('Microsoft.XMLHTTP');
diff --git a/src/Symfony/Component/Console/CHANGELOG.md b/src/Symfony/Component/Console/CHANGELOG.md
index 90eb1152e4..c631f46071 100644
--- a/src/Symfony/Component/Console/CHANGELOG.md
+++ b/src/Symfony/Component/Console/CHANGELOG.md
@@ -17,6 +17,10 @@ CHANGELOG
  * added `CommandLoaderInterface`, `FactoryCommandLoader` and PSR-11
    `ContainerCommandLoader` for commands lazy-loading
  * added a case-insensitive command name matching fallback
+ * added static `Command::$defaultName/getDefaultName()`, allowing for
+   commands to be registered at compile time in the application command loader.
+   Setting the `$defaultName` property avoids the need for filling the `command`
+   attribute on the `console.command` tag when using `AddConsoleCommandPass`.
 
 3.3.0
 -----
diff --git a/src/Symfony/Component/Console/Command/Command.php b/src/Symfony/Component/Console/Command/Command.php
index f3a5d716f2..c75bf4e361 100644
--- a/src/Symfony/Component/Console/Command/Command.php
+++ b/src/Symfony/Component/Console/Command/Command.php
@@ -29,6 +29,11 @@ use Symfony\Component\Console\Exception\LogicException;
  */
 class Command
 {
+    /**
+     * @var string|null The default command name
+     */
+    protected static $defaultName;
+
     private $application;
     private $name;
     private $processTitle;
@@ -45,6 +50,17 @@ class Command
     private $usages = array();
     private $helperSet;
 
+    /**
+     * @return string|null The default command name or null when no default name is set
+     */
+    public static function getDefaultName()
+    {
+        $class = get_called_class();
+        $r = new \ReflectionProperty($class, 'defaultName');
+
+        return $class === $r->class ? static::$defaultName : null;
+    }
+
     /**
      * Constructor.
      *
@@ -56,7 +72,7 @@ class Command
     {
         $this->definition = new InputDefinition();
 
-        if (null !== $name) {
+        if (null !== $name || null !== $name = static::getDefaultName()) {
             $this->setName($name);
         }
 
diff --git a/src/Symfony/Component/Console/DependencyInjection/AddConsoleCommandPass.php b/src/Symfony/Component/Console/DependencyInjection/AddConsoleCommandPass.php
index 67034098c2..add7c5d0df 100644
--- a/src/Symfony/Component/Console/DependencyInjection/AddConsoleCommandPass.php
+++ b/src/Symfony/Component/Console/DependencyInjection/AddConsoleCommandPass.php
@@ -46,16 +46,21 @@ class AddConsoleCommandPass implements CompilerPassInterface
             $definition = $container->getDefinition($id);
             $class = $container->getParameterBag()->resolveValue($definition->getClass());
 
-            if (!$r = $container->getReflectionClass($class)) {
-                throw new InvalidArgumentException(sprintf('Class "%s" used for service "%s" cannot be found.', $class, $id));
-            }
-            if (!$r->isSubclassOf(Command::class)) {
-                throw new InvalidArgumentException(sprintf('The service "%s" tagged "%s" must be a subclass of "%s".', $id, $this->commandTag, Command::class));
-            }
-
             $commandId = 'console.command.'.strtolower(str_replace('\\', '_', $class));
 
-            if (!isset($tags[0]['command'])) {
+            if (isset($tags[0]['command'])) {
+                $commandName = $tags[0]['command'];
+            } else {
+                if (!$r = $container->getReflectionClass($class)) {
+                    throw new InvalidArgumentException(sprintf('Class "%s" used for service "%s" cannot be found.', $class, $id));
+                }
+                if (!$r->isSubclassOf(Command::class)) {
+                    throw new InvalidArgumentException(sprintf('The service "%s" tagged "%s" must be a subclass of "%s".', $id, $this->commandTag, Command::class));
+                }
+                $commandName = $class::getDefaultName();
+            }
+
+            if (null === $commandName) {
                 if (isset($serviceIds[$commandId]) || $container->hasAlias($commandId)) {
                     $commandId = $commandId.'_'.$id;
                 }
@@ -69,7 +74,6 @@ class AddConsoleCommandPass implements CompilerPassInterface
             }
 
             $serviceIds[$commandId] = false;
-            $commandName = $tags[0]['command'];
             unset($tags[0]);
             $lazyCommandMap[$commandName] = $id;
             $lazyCommandRefs[$id] = new TypedReference($id, $class);
diff --git a/src/Symfony/Component/Console/Tests/DependencyInjection/AddConsoleCommandPassTest.php b/src/Symfony/Component/Console/Tests/DependencyInjection/AddConsoleCommandPassTest.php
index ddcee80145..807eb38973 100644
--- a/src/Symfony/Component/Console/Tests/DependencyInjection/AddConsoleCommandPassTest.php
+++ b/src/Symfony/Component/Console/Tests/DependencyInjection/AddConsoleCommandPassTest.php
@@ -77,6 +77,38 @@ class AddConsoleCommandPassTest extends TestCase
         $this->assertSame(array(array('setName', array('my:command')), array('setAliases', array(array('my:alias')))), $command->getMethodCalls());
     }
 
+    public function testProcessFallsBackToDefaultName()
+    {
+        $container = new ContainerBuilder();
+        $container
+            ->register('with-default-name', NamedCommand::class)
+            ->setPublic(false)
+            ->addTag('console.command')
+        ;
+
+        $pass = new AddConsoleCommandPass();
+        $pass->process($container);
+
+        $commandLoader = $container->getDefinition('console.command_loader');
+        $commandLocator = $container->getDefinition((string) $commandLoader->getArgument(0));
+
+        $this->assertSame(ContainerCommandLoader::class, $commandLoader->getClass());
+        $this->assertSame(array('default' => 'with-default-name'), $commandLoader->getArgument(1));
+        $this->assertEquals(array(array('with-default-name' => new ServiceClosureArgument(new TypedReference('with-default-name', NamedCommand::class)))), $commandLocator->getArguments());
+        $this->assertSame(array('console.command.symfony_component_console_tests_dependencyinjection_namedcommand' => false), $container->getParameter('console.command.ids'));
+
+        $container = new ContainerBuilder();
+        $container
+            ->register('with-default-name', NamedCommand::class)
+            ->setPublic(false)
+            ->addTag('console.command', array('command' => 'new-name'))
+        ;
+
+        $pass->process($container);
+
+        $this->assertSame(array('new-name' => 'with-default-name'), $container->getDefinition('console.command_loader')->getArgument(1));
+    }
+
     public function visibilityProvider()
     {
         return array(
@@ -96,7 +128,7 @@ class AddConsoleCommandPassTest extends TestCase
         $container->addCompilerPass(new AddConsoleCommandPass());
 
         $definition = new Definition('Symfony\Component\Console\Tests\DependencyInjection\MyCommand');
-        $definition->addTag('console.command', array('command' => 'my:command'));
+        $definition->addTag('console.command');
         $definition->setAbstract(true);
         $container->setDefinition('my-command', $definition);
 
@@ -114,7 +146,7 @@ class AddConsoleCommandPassTest extends TestCase
         $container->addCompilerPass(new AddConsoleCommandPass());
 
         $definition = new Definition('SplObjectStorage');
-        $definition->addTag('console.command', array('command' => 'my:command'));
+        $definition->addTag('console.command');
         $container->setDefinition('my-command', $definition);
 
         $container->compile();
@@ -146,3 +178,8 @@ class AddConsoleCommandPassTest extends TestCase
 class MyCommand extends Command
 {
 }
+
+class NamedCommand extends Command
+{
+    protected static $defaultName = 'default';
+}
diff --git a/src/Symfony/Component/DependencyInjection/CHANGELOG.md b/src/Symfony/Component/DependencyInjection/CHANGELOG.md
index 3d2c56a5c8..1e51a5c927 100644
--- a/src/Symfony/Component/DependencyInjection/CHANGELOG.md
+++ b/src/Symfony/Component/DependencyInjection/CHANGELOG.md
@@ -28,6 +28,7 @@ CHANGELOG
  * deprecated service auto-registration while autowiring
  * deprecated the ability to check for the initialization of a private service with the `Container::initialized()` method
  * deprecated support for top-level anonymous services in XML
+ * deprecated case insensitivity of parameter names
 
 3.3.0
 -----
diff --git a/src/Symfony/Component/DependencyInjection/Dumper/PhpDumper.php b/src/Symfony/Component/DependencyInjection/Dumper/PhpDumper.php
index aba675ab95..93a0ccda3e 100644
--- a/src/Symfony/Component/DependencyInjection/Dumper/PhpDumper.php
+++ b/src/Symfony/Component/DependencyInjection/Dumper/PhpDumper.php
@@ -1039,11 +1039,15 @@ EOF;
 
         $php = array();
         $dynamicPhp = array();
+        $normalizedParams = array();
 
         foreach ($this->container->getParameterBag()->all() as $key => $value) {
             if ($key !== $resolvedKey = $this->container->resolveEnvPlaceholders($key)) {
                 throw new InvalidArgumentException(sprintf('Parameter name cannot use env parameters: %s.', $resolvedKey));
             }
+            if ($key !== $lcKey = strtolower($key)) {
+                $normalizedParams[] = sprintf('        %s => %s,', $this->export($lcKey), $this->export($key));
+            }
             $export = $this->exportParameters(array($value));
             $export = explode('0 => ', substr(rtrim($export, " )\n"), 7, -1), 2);
 
@@ -1063,7 +1067,7 @@ EOF;
     public function getParameter($name)
     {
         if (!(isset($this->parameters[$name]) || isset($this->loadedDynamicParameters[$name]) || array_key_exists($name, $this->parameters))) {
-            $name = strtolower($name);
+            $name = $this->normalizeParameterName($name);
 
             if (!(isset($this->parameters[$name]) || isset($this->loadedDynamicParameters[$name]) || array_key_exists($name, $this->parameters))) {
                 throw new InvalidArgumentException(sprintf('The parameter "%s" must be defined.', $name));
@@ -1081,7 +1085,7 @@ EOF;
      */
     public function hasParameter($name)
     {
-        $name = strtolower($name);
+        $name = $this->normalizeParameterName($name);
 
         return isset($this->parameters[$name]) || isset($this->loadedDynamicParameters[$name]) || array_key_exists($name, $this->parameters);
     }
@@ -1151,6 +1155,30 @@ EOF;
 {$getDynamicParameter}
     }
 
+
+EOF;
+
+        $code .= '    private $normalizedParameterNames = '.($normalizedParams ? sprintf("array(\n%s\n    );", implode("\n", $normalizedParams)) : 'array();')."\n";
+        $code .= <<<'EOF'
+
+    private function normalizeParameterName($name)
+    {
+        if (isset($this->normalizedParameterNames[$normalizedName = strtolower($name)]) || isset($this->parameters[$normalizedName]) || array_key_exists($normalizedName, $this->parameters)) {
+            $normalizedName = isset($this->normalizedParameterNames[$normalizedName]) ? $this->normalizedParameterNames[$normalizedName] : $normalizedName;
+            if ((string) $name !== $normalizedName) {
+                @trigger_error(sprintf('Parameter names will be made case sensitive in Symfony 4.0. Using "%s" instead of "%s" is deprecated since version 3.4.', $name, $normalizedName), E_USER_DEPRECATED);
+            }
+        } else {
+            $normalizedName = $this->normalizedParameterNames[$normalizedName] = (string) $name;
+        }
+
+        return $normalizedName;
+    }
+
+EOF;
+
+        $code .= <<<EOF
+
     /*{$this->docStar}
      * Gets the default parameters.
      *
@@ -1533,10 +1561,10 @@ EOF;
             if (preg_match('/^%([^%]+)%$/', $value, $match)) {
                 // we do this to deal with non string values (Boolean, integer, ...)
                 // the preg_replace_callback converts them to strings
-                return $this->dumpParameter(strtolower($match[1]));
+                return $this->dumpParameter($match[1]);
             } else {
                 $replaceParameters = function ($match) {
-                    return "'.".$this->dumpParameter(strtolower($match[2])).".'";
+                    return "'.".$this->dumpParameter($match[2]).".'";
                 };
 
                 $code = str_replace('%%', '%', preg_replace_callback('/(?<!%)(%)([^%]+)\1/', $replaceParameters, $this->export($value)));
@@ -1582,8 +1610,6 @@ EOF;
      */
     private function dumpParameter($name)
     {
-        $name = strtolower($name);
-
         if ($this->container->isCompiled() && $this->container->hasParameter($name)) {
             $value = $this->container->getParameter($name);
             $dumpedValue = $this->dumpValue($value, false);
diff --git a/src/Symfony/Component/DependencyInjection/Loader/XmlFileLoader.php b/src/Symfony/Component/DependencyInjection/Loader/XmlFileLoader.php
index f620f0785d..b1dc2b566a 100644
--- a/src/Symfony/Component/DependencyInjection/Loader/XmlFileLoader.php
+++ b/src/Symfony/Component/DependencyInjection/Loader/XmlFileLoader.php
@@ -471,11 +471,6 @@ class XmlFileLoader extends FileLoader
                 $key = array_pop($keys);
             } else {
                 $key = $arg->getAttribute('key');
-
-                // parameter keys are case insensitive
-                if ('parameter' == $name && $lowercase) {
-                    $key = strtolower($key);
-                }
             }
 
             $onInvalid = $arg->getAttribute('on-invalid');
@@ -579,7 +574,7 @@ class XmlFileLoader extends FileLoader
         foreach ($schemaLocations as $namespace => $location) {
             $parts = explode('/', $location);
             if (0 === stripos($location, 'phar://')) {
-                $tmpfile = tempnam(sys_get_temp_dir(), 'sf2');
+                $tmpfile = tempnam(sys_get_temp_dir(), 'symfony');
                 if ($tmpfile) {
                     copy($location, $tmpfile);
                     $tmpfiles[] = $tmpfile;
diff --git a/src/Symfony/Component/DependencyInjection/ParameterBag/EnvPlaceholderParameterBag.php b/src/Symfony/Component/DependencyInjection/ParameterBag/EnvPlaceholderParameterBag.php
index d20e53531a..fd859068be 100644
--- a/src/Symfony/Component/DependencyInjection/ParameterBag/EnvPlaceholderParameterBag.php
+++ b/src/Symfony/Component/DependencyInjection/ParameterBag/EnvPlaceholderParameterBag.php
@@ -91,7 +91,7 @@ class EnvPlaceholderParameterBag extends ParameterBag
         parent::resolve();
 
         foreach ($this->envPlaceholders as $env => $placeholders) {
-            if (!isset($this->parameters[$name = strtolower("env($env)")])) {
+            if (!$this->has($name = "env($env)")) {
                 continue;
             }
             if (is_numeric($default = $this->parameters[$name])) {
diff --git a/src/Symfony/Component/DependencyInjection/ParameterBag/ParameterBag.php b/src/Symfony/Component/DependencyInjection/ParameterBag/ParameterBag.php
index 83ba7e7076..1a9ca6fa4d 100644
--- a/src/Symfony/Component/DependencyInjection/ParameterBag/ParameterBag.php
+++ b/src/Symfony/Component/DependencyInjection/ParameterBag/ParameterBag.php
@@ -25,6 +25,8 @@ class ParameterBag implements ParameterBagInterface
     protected $parameters = array();
     protected $resolved = false;
 
+    private $normalizedNames = array();
+
     /**
      * @param array $parameters An array of parameters
      */
@@ -49,7 +51,7 @@ class ParameterBag implements ParameterBagInterface
     public function add(array $parameters)
     {
         foreach ($parameters as $key => $value) {
-            $this->parameters[strtolower($key)] = $value;
+            $this->set($key, $value);
         }
     }
 
@@ -66,7 +68,7 @@ class ParameterBag implements ParameterBagInterface
      */
     public function get($name)
     {
-        $name = strtolower($name);
+        $name = $this->normalizeName($name);
 
         if (!array_key_exists($name, $this->parameters)) {
             if (!$name) {
@@ -111,7 +113,7 @@ class ParameterBag implements ParameterBagInterface
      */
     public function set($name, $value)
     {
-        $this->parameters[strtolower($name)] = $value;
+        $this->parameters[$this->normalizeName($name)] = $value;
     }
 
     /**
@@ -119,7 +121,7 @@ class ParameterBag implements ParameterBagInterface
      */
     public function has($name)
     {
-        return array_key_exists(strtolower($name), $this->parameters);
+        return array_key_exists($this->normalizeName($name), $this->parameters);
     }
 
     /**
@@ -129,7 +131,7 @@ class ParameterBag implements ParameterBagInterface
      */
     public function remove($name)
     {
-        unset($this->parameters[strtolower($name)]);
+        unset($this->parameters[$this->normalizeName($name)]);
     }
 
     /**
@@ -206,7 +208,7 @@ class ParameterBag implements ParameterBagInterface
         // a non-string in a parameter value
         if (preg_match('/^%([^%\s]+)%$/', $value, $match)) {
             $key = $match[1];
-            $lcKey = strtolower($key);
+            $lcKey = strtolower($key); // strtolower() to be removed in 4.0
 
             if (isset($resolving[$lcKey])) {
                 throw new ParameterCircularReferenceException(array_keys($resolving));
@@ -224,7 +226,7 @@ class ParameterBag implements ParameterBagInterface
             }
 
             $key = $match[1];
-            $lcKey = strtolower($key);
+            $lcKey = strtolower($key); // strtolower() to be removed in 4.0
             if (isset($resolving[$lcKey])) {
                 throw new ParameterCircularReferenceException(array_keys($resolving));
             }
@@ -288,4 +290,18 @@ class ParameterBag implements ParameterBagInterface
 
         return $value;
     }
+
+    private function normalizeName($name)
+    {
+        if (isset($this->normalizedNames[$normalizedName = strtolower($name)])) {
+            $normalizedName = $this->normalizedNames[$normalizedName];
+            if ((string) $name !== $normalizedName) {
+                @trigger_error(sprintf('Parameter names will be made case sensitive in Symfony 4.0. Using "%s" instead of "%s" is deprecated since version 3.4.', $name, $normalizedName), E_USER_DEPRECATED);
+            }
+        } else {
+            $normalizedName = $this->normalizedNames[$normalizedName] = (string) $name;
+        }
+
+        return $normalizedName;
+    }
 }
diff --git a/src/Symfony/Component/DependencyInjection/Tests/ContainerBuilderTest.php b/src/Symfony/Component/DependencyInjection/Tests/ContainerBuilderTest.php
index 29073b276f..d48c2460dc 100644
--- a/src/Symfony/Component/DependencyInjection/Tests/ContainerBuilderTest.php
+++ b/src/Symfony/Component/DependencyInjection/Tests/ContainerBuilderTest.php
@@ -1097,6 +1097,21 @@ class ContainerBuilderTest extends TestCase
         $this->assertNotSame($container->get('foo'), $container->get('fOO'), '->get() returns the service for the given id, case sensitively');
         $this->assertSame($container->get('fOO')->Foo->foo, $container->get('foo'), '->get() returns the service for the given id, case sensitively');
     }
+
+    /**
+     * @group legacy
+     * @expectedDeprecation Parameter names will be made case sensitive in Symfony 4.0. Using "FOO" instead of "foo" is deprecated since version 3.4.
+     */
+    public function testParameterWithMixedCase()
+    {
+        $container = new ContainerBuilder(new ParameterBag(array('foo' => 'bar')));
+        $container->register('foo', 'stdClass')
+            ->setProperty('foo', '%FOO%');
+
+        $container->compile();
+
+        $this->assertSame('bar', $container->get('foo')->foo);
+    }
 }
 
 class FooClass
diff --git a/src/Symfony/Component/DependencyInjection/Tests/ContainerTest.php b/src/Symfony/Component/DependencyInjection/Tests/ContainerTest.php
index 46780ed3f0..30eefb5546 100644
--- a/src/Symfony/Component/DependencyInjection/Tests/ContainerTest.php
+++ b/src/Symfony/Component/DependencyInjection/Tests/ContainerTest.php
@@ -112,10 +112,6 @@ class ContainerTest extends TestCase
         $sc->setParameter('foo', 'baz');
         $this->assertEquals('baz', $sc->getParameter('foo'), '->setParameter() overrides previously set parameter');
 
-        $sc->setParameter('Foo', 'baz1');
-        $this->assertEquals('baz1', $sc->getParameter('foo'), '->setParameter() converts the key to lowercase');
-        $this->assertEquals('baz1', $sc->getParameter('FOO'), '->getParameter() converts the key to lowercase');
-
         try {
             $sc->getParameter('baba');
             $this->fail('->getParameter() thrown an \InvalidArgumentException if the key does not exist');
@@ -125,6 +121,20 @@ class ContainerTest extends TestCase
         }
     }
 
+    /**
+     * @group legacy
+     * @expectedDeprecation Parameter names will be made case sensitive in Symfony 4.0. Using "Foo" instead of "foo" is deprecated since version 3.4.
+     * @expectedDeprecation Parameter names will be made case sensitive in Symfony 4.0. Using "FOO" instead of "foo" is deprecated since version 3.4.
+     */
+    public function testGetSetParameterWithMixedCase()
+    {
+        $sc = new Container(new ParameterBag(array('foo' => 'bar')));
+
+        $sc->setParameter('Foo', 'baz1');
+        $this->assertEquals('baz1', $sc->getParameter('foo'), '->setParameter() converts the key to lowercase');
+        $this->assertEquals('baz1', $sc->getParameter('FOO'), '->getParameter() converts the key to lowercase');
+    }
+
     public function testGetServiceIds()
     {
         $sc = new Container();
diff --git a/src/Symfony/Component/DependencyInjection/Tests/Dumper/PhpDumperTest.php b/src/Symfony/Component/DependencyInjection/Tests/Dumper/PhpDumperTest.php
index 4f4cf9936b..47356e2d5c 100644
--- a/src/Symfony/Component/DependencyInjection/Tests/Dumper/PhpDumperTest.php
+++ b/src/Symfony/Component/DependencyInjection/Tests/Dumper/PhpDumperTest.php
@@ -650,4 +650,43 @@ class PhpDumperTest extends TestCase
 
         $container->get('bar');
     }
+
+    /**
+     * @group legacy
+     * @expectedDeprecation Parameter names will be made case sensitive in Symfony 4.0. Using "foo" instead of "Foo" is deprecated since version 3.4.
+     * @expectedDeprecation Parameter names will be made case sensitive in Symfony 4.0. Using "FOO" instead of "Foo" is deprecated since version 3.4.
+     * @expectedDeprecation Parameter names will be made case sensitive in Symfony 4.0. Using "bar" instead of "BAR" is deprecated since version 3.4.
+     */
+    public function testParameterWithMixedCase()
+    {
+        $container = new ContainerBuilder(new ParameterBag(array('Foo' => 'bar', 'BAR' => 'foo')));
+        $container->compile();
+
+        $dumper = new PhpDumper($container);
+        eval('?>'.$dumper->dump(array('class' => 'Symfony_DI_PhpDumper_Test_Parameter_With_Mixed_Case')));
+
+        $container = new \Symfony_DI_PhpDumper_Test_Parameter_With_Mixed_Case();
+
+        $this->assertSame('bar', $container->getParameter('foo'));
+        $this->assertSame('bar', $container->getParameter('FOO'));
+        $this->assertSame('foo', $container->getParameter('bar'));
+        $this->assertSame('foo', $container->getParameter('BAR'));
+    }
+
+    /**
+     * @group legacy
+     * @expectedDeprecation Parameter names will be made case sensitive in Symfony 4.0. Using "FOO" instead of "foo" is deprecated since version 3.4.
+     */
+    public function testParameterWithLowerCase()
+    {
+        $container = new ContainerBuilder(new ParameterBag(array('foo' => 'bar')));
+        $container->compile();
+
+        $dumper = new PhpDumper($container);
+        eval('?>'.$dumper->dump(array('class' => 'Symfony_DI_PhpDumper_Test_Parameter_With_Lower_Case')));
+
+        $container = new \Symfony_DI_PhpDumper_Test_Parameter_With_Lower_Case();
+
+        $this->assertSame('bar', $container->getParameter('FOO'));
+    }
 }
diff --git a/src/Symfony/Component/DependencyInjection/Tests/Fixtures/containers/container8.php b/src/Symfony/Component/DependencyInjection/Tests/Fixtures/containers/container8.php
index f0b4ca9330..1a4e5ab5c8 100644
--- a/src/Symfony/Component/DependencyInjection/Tests/Fixtures/containers/container8.php
+++ b/src/Symfony/Component/DependencyInjection/Tests/Fixtures/containers/container8.php
@@ -4,7 +4,7 @@ use Symfony\Component\DependencyInjection\ContainerBuilder;
 use Symfony\Component\DependencyInjection\ParameterBag\ParameterBag;
 
 $container = new ContainerBuilder(new ParameterBag(array(
-    'FOO' => '%baz%',
+    'foo' => '%baz%',
     'baz' => 'bar',
     'bar' => 'foo is %%foo bar',
     'escape' => '@escapeme',
diff --git a/src/Symfony/Component/DependencyInjection/Tests/Fixtures/php/services10.php b/src/Symfony/Component/DependencyInjection/Tests/Fixtures/php/services10.php
index 9f79c99317..582472b38b 100644
--- a/src/Symfony/Component/DependencyInjection/Tests/Fixtures/php/services10.php
+++ b/src/Symfony/Component/DependencyInjection/Tests/Fixtures/php/services10.php
@@ -78,7 +78,7 @@ class ProjectServiceContainer extends Container
     public function getParameter($name)
     {
         if (!(isset($this->parameters[$name]) || isset($this->loadedDynamicParameters[$name]) || array_key_exists($name, $this->parameters))) {
-            $name = strtolower($name);
+            $name = $this->normalizeParameterName($name);
 
             if (!(isset($this->parameters[$name]) || isset($this->loadedDynamicParameters[$name]) || array_key_exists($name, $this->parameters))) {
                 throw new InvalidArgumentException(sprintf('The parameter "%s" must be defined.', $name));
@@ -96,7 +96,7 @@ class ProjectServiceContainer extends Container
      */
     public function hasParameter($name)
     {
-        $name = strtolower($name);
+        $name = $this->normalizeParameterName($name);
 
         return isset($this->parameters[$name]) || isset($this->loadedDynamicParameters[$name]) || array_key_exists($name, $this->parameters);
     }
@@ -142,6 +142,22 @@ class ProjectServiceContainer extends Container
         throw new InvalidArgumentException(sprintf('The dynamic parameter "%s" must be defined.', $name));
     }
 
+    private $normalizedParameterNames = array();
+
+    private function normalizeParameterName($name)
+    {
+        if (isset($this->normalizedParameterNames[$normalizedName = strtolower($name)]) || isset($this->parameters[$normalizedName]) || array_key_exists($normalizedName, $this->parameters)) {
+            $normalizedName = isset($this->normalizedParameterNames[$normalizedName]) ? $this->normalizedParameterNames[$normalizedName] : $normalizedName;
+            if ((string) $name !== $normalizedName) {
+                @trigger_error(sprintf('Parameter names will be made case sensitive in Symfony 4.0. Using "%s" instead of "%s" is deprecated since version 3.4.', $name, $normalizedName), E_USER_DEPRECATED);
+            }
+        } else {
+            $normalizedName = $this->normalizedParameterNames[$normalizedName] = (string) $name;
+        }
+
+        return $normalizedName;
+    }
+
     /**
      * Gets the default parameters.
      *
diff --git a/src/Symfony/Component/DependencyInjection/Tests/Fixtures/php/services12.php b/src/Symfony/Component/DependencyInjection/Tests/Fixtures/php/services12.php
index 05bd46c18d..f5db7d75d4 100644
--- a/src/Symfony/Component/DependencyInjection/Tests/Fixtures/php/services12.php
+++ b/src/Symfony/Component/DependencyInjection/Tests/Fixtures/php/services12.php
@@ -82,7 +82,7 @@ class ProjectServiceContainer extends Container
     public function getParameter($name)
     {
         if (!(isset($this->parameters[$name]) || isset($this->loadedDynamicParameters[$name]) || array_key_exists($name, $this->parameters))) {
-            $name = strtolower($name);
+            $name = $this->normalizeParameterName($name);
 
             if (!(isset($this->parameters[$name]) || isset($this->loadedDynamicParameters[$name]) || array_key_exists($name, $this->parameters))) {
                 throw new InvalidArgumentException(sprintf('The parameter "%s" must be defined.', $name));
@@ -100,7 +100,7 @@ class ProjectServiceContainer extends Container
      */
     public function hasParameter($name)
     {
-        $name = strtolower($name);
+        $name = $this->normalizeParameterName($name);
 
         return isset($this->parameters[$name]) || isset($this->loadedDynamicParameters[$name]) || array_key_exists($name, $this->parameters);
     }
@@ -156,6 +156,22 @@ class ProjectServiceContainer extends Container
         return $this->dynamicParameters[$name] = $value;
     }
 
+    private $normalizedParameterNames = array();
+
+    private function normalizeParameterName($name)
+    {
+        if (isset($this->normalizedParameterNames[$normalizedName = strtolower($name)]) || isset($this->parameters[$normalizedName]) || array_key_exists($normalizedName, $this->parameters)) {
+            $normalizedName = isset($this->normalizedParameterNames[$normalizedName]) ? $this->normalizedParameterNames[$normalizedName] : $normalizedName;
+            if ((string) $name !== $normalizedName) {
+                @trigger_error(sprintf('Parameter names will be made case sensitive in Symfony 4.0. Using "%s" instead of "%s" is deprecated since version 3.4.', $name, $normalizedName), E_USER_DEPRECATED);
+            }
+        } else {
+            $normalizedName = $this->normalizedParameterNames[$normalizedName] = (string) $name;
+        }
+
+        return $normalizedName;
+    }
+
     /**
      * Gets the default parameters.
      *
diff --git a/src/Symfony/Component/DependencyInjection/Tests/Fixtures/php/services26.php b/src/Symfony/Component/DependencyInjection/Tests/Fixtures/php/services26.php
index a2e3937d12..f7eb32e55e 100644
--- a/src/Symfony/Component/DependencyInjection/Tests/Fixtures/php/services26.php
+++ b/src/Symfony/Component/DependencyInjection/Tests/Fixtures/php/services26.php
@@ -80,7 +80,7 @@ class ProjectServiceContainer extends Container
     public function getParameter($name)
     {
         if (!(isset($this->parameters[$name]) || isset($this->loadedDynamicParameters[$name]) || array_key_exists($name, $this->parameters))) {
-            $name = strtolower($name);
+            $name = $this->normalizeParameterName($name);
 
             if (!(isset($this->parameters[$name]) || isset($this->loadedDynamicParameters[$name]) || array_key_exists($name, $this->parameters))) {
                 throw new InvalidArgumentException(sprintf('The parameter "%s" must be defined.', $name));
@@ -98,7 +98,7 @@ class ProjectServiceContainer extends Container
      */
     public function hasParameter($name)
     {
-        $name = strtolower($name);
+        $name = $this->normalizeParameterName($name);
 
         return isset($this->parameters[$name]) || isset($this->loadedDynamicParameters[$name]) || array_key_exists($name, $this->parameters);
     }
@@ -152,6 +152,24 @@ class ProjectServiceContainer extends Container
         return $this->dynamicParameters[$name] = $value;
     }
 
+    private $normalizedParameterNames = array(
+        'env(foo)' => 'env(FOO)',
+    );
+
+    private function normalizeParameterName($name)
+    {
+        if (isset($this->normalizedParameterNames[$normalizedName = strtolower($name)]) || isset($this->parameters[$normalizedName]) || array_key_exists($normalizedName, $this->parameters)) {
+            $normalizedName = isset($this->normalizedParameterNames[$normalizedName]) ? $this->normalizedParameterNames[$normalizedName] : $normalizedName;
+            if ((string) $name !== $normalizedName) {
+                @trigger_error(sprintf('Parameter names will be made case sensitive in Symfony 4.0. Using "%s" instead of "%s" is deprecated since version 3.4.', $name, $normalizedName), E_USER_DEPRECATED);
+            }
+        } else {
+            $normalizedName = $this->normalizedParameterNames[$normalizedName] = (string) $name;
+        }
+
+        return $normalizedName;
+    }
+
     /**
      * Gets the default parameters.
      *
@@ -160,7 +178,7 @@ class ProjectServiceContainer extends Container
     protected function getDefaultParameters()
     {
         return array(
-            'env(foo)' => 'foo',
+            'env(FOO)' => 'foo',
         );
     }
 }
diff --git a/src/Symfony/Component/DependencyInjection/Tests/Fixtures/php/services8.php b/src/Symfony/Component/DependencyInjection/Tests/Fixtures/php/services8.php
index 004c7b8008..bbd0b34c58 100644
--- a/src/Symfony/Component/DependencyInjection/Tests/Fixtures/php/services8.php
+++ b/src/Symfony/Component/DependencyInjection/Tests/Fixtures/php/services8.php
@@ -65,7 +65,7 @@ class ProjectServiceContainer extends Container
     public function getParameter($name)
     {
         if (!(isset($this->parameters[$name]) || isset($this->loadedDynamicParameters[$name]) || array_key_exists($name, $this->parameters))) {
-            $name = strtolower($name);
+            $name = $this->normalizeParameterName($name);
 
             if (!(isset($this->parameters[$name]) || isset($this->loadedDynamicParameters[$name]) || array_key_exists($name, $this->parameters))) {
                 throw new InvalidArgumentException(sprintf('The parameter "%s" must be defined.', $name));
@@ -83,7 +83,7 @@ class ProjectServiceContainer extends Container
      */
     public function hasParameter($name)
     {
-        $name = strtolower($name);
+        $name = $this->normalizeParameterName($name);
 
         return isset($this->parameters[$name]) || isset($this->loadedDynamicParameters[$name]) || array_key_exists($name, $this->parameters);
     }
@@ -129,6 +129,22 @@ class ProjectServiceContainer extends Container
         throw new InvalidArgumentException(sprintf('The dynamic parameter "%s" must be defined.', $name));
     }
 
+    private $normalizedParameterNames = array();
+
+    private function normalizeParameterName($name)
+    {
+        if (isset($this->normalizedParameterNames[$normalizedName = strtolower($name)]) || isset($this->parameters[$normalizedName]) || array_key_exists($normalizedName, $this->parameters)) {
+            $normalizedName = isset($this->normalizedParameterNames[$normalizedName]) ? $this->normalizedParameterNames[$normalizedName] : $normalizedName;
+            if ((string) $name !== $normalizedName) {
+                @trigger_error(sprintf('Parameter names will be made case sensitive in Symfony 4.0. Using "%s" instead of "%s" is deprecated since version 3.4.', $name, $normalizedName), E_USER_DEPRECATED);
+            }
+        } else {
+            $normalizedName = $this->normalizedParameterNames[$normalizedName] = (string) $name;
+        }
+
+        return $normalizedName;
+    }
+
     /**
      * Gets the default parameters.
      *
diff --git a/src/Symfony/Component/DependencyInjection/Tests/Fixtures/php/services9_as_files.txt b/src/Symfony/Component/DependencyInjection/Tests/Fixtures/php/services9_as_files.txt
index 13cfae45af..d5f8d4f65e 100644
--- a/src/Symfony/Component/DependencyInjection/Tests/Fixtures/php/services9_as_files.txt
+++ b/src/Symfony/Component/DependencyInjection/Tests/Fixtures/php/services9_as_files.txt
@@ -383,7 +383,7 @@ class Container%s extends Container
     public function getParameter($name)
     {
         if (!(isset($this->parameters[$name]) || isset($this->loadedDynamicParameters[$name]) || array_key_exists($name, $this->parameters))) {
-            $name = strtolower($name);
+            $name = $this->normalizeParameterName($name);
 
             if (!(isset($this->parameters[$name]) || isset($this->loadedDynamicParameters[$name]) || array_key_exists($name, $this->parameters))) {
                 throw new InvalidArgumentException(sprintf('The parameter "%s" must be defined.', $name));
@@ -401,7 +401,7 @@ class Container%s extends Container
      */
     public function hasParameter($name)
     {
-        $name = strtolower($name);
+        $name = $this->normalizeParameterName($name);
 
         return isset($this->parameters[$name]) || isset($this->loadedDynamicParameters[$name]) || array_key_exists($name, $this->parameters);
     }
@@ -447,6 +447,22 @@ class Container%s extends Container
         throw new InvalidArgumentException(sprintf('The dynamic parameter "%s" must be defined.', $name));
     }
 
+    private $normalizedParameterNames = array();
+
+    private function normalizeParameterName($name)
+    {
+        if (isset($this->normalizedParameterNames[$normalizedName = strtolower($name)]) || isset($this->parameters[$normalizedName]) || array_key_exists($normalizedName, $this->parameters)) {
+            $normalizedName = isset($this->normalizedParameterNames[$normalizedName]) ? $this->normalizedParameterNames[$normalizedName] : $normalizedName;
+            if ((string) $name !== $normalizedName) {
+                @trigger_error(sprintf('Parameter names will be made case sensitive in Symfony 4.0. Using "%s" instead of "%s" is deprecated since version 3.4.', $name, $normalizedName), E_USER_DEPRECATED);
+            }
+        } else {
+            $normalizedName = $this->normalizedParameterNames[$normalizedName] = (string) $name;
+        }
+
+        return $normalizedName;
+    }
+
     /**
      * Gets the default parameters.
      *
diff --git a/src/Symfony/Component/DependencyInjection/Tests/Fixtures/php/services9_compiled.php b/src/Symfony/Component/DependencyInjection/Tests/Fixtures/php/services9_compiled.php
index 847b722792..30f58e1d97 100644
--- a/src/Symfony/Component/DependencyInjection/Tests/Fixtures/php/services9_compiled.php
+++ b/src/Symfony/Component/DependencyInjection/Tests/Fixtures/php/services9_compiled.php
@@ -392,7 +392,7 @@ class ProjectServiceContainer extends Container
     public function getParameter($name)
     {
         if (!(isset($this->parameters[$name]) || isset($this->loadedDynamicParameters[$name]) || array_key_exists($name, $this->parameters))) {
-            $name = strtolower($name);
+            $name = $this->normalizeParameterName($name);
 
             if (!(isset($this->parameters[$name]) || isset($this->loadedDynamicParameters[$name]) || array_key_exists($name, $this->parameters))) {
                 throw new InvalidArgumentException(sprintf('The parameter "%s" must be defined.', $name));
@@ -410,7 +410,7 @@ class ProjectServiceContainer extends Container
      */
     public function hasParameter($name)
     {
-        $name = strtolower($name);
+        $name = $this->normalizeParameterName($name);
 
         return isset($this->parameters[$name]) || isset($this->loadedDynamicParameters[$name]) || array_key_exists($name, $this->parameters);
     }
@@ -456,6 +456,22 @@ class ProjectServiceContainer extends Container
         throw new InvalidArgumentException(sprintf('The dynamic parameter "%s" must be defined.', $name));
     }
 
+    private $normalizedParameterNames = array();
+
+    private function normalizeParameterName($name)
+    {
+        if (isset($this->normalizedParameterNames[$normalizedName = strtolower($name)]) || isset($this->parameters[$normalizedName]) || array_key_exists($normalizedName, $this->parameters)) {
+            $normalizedName = isset($this->normalizedParameterNames[$normalizedName]) ? $this->normalizedParameterNames[$normalizedName] : $normalizedName;
+            if ((string) $name !== $normalizedName) {
+                @trigger_error(sprintf('Parameter names will be made case sensitive in Symfony 4.0. Using "%s" instead of "%s" is deprecated since version 3.4.', $name, $normalizedName), E_USER_DEPRECATED);
+            }
+        } else {
+            $normalizedName = $this->normalizedParameterNames[$normalizedName] = (string) $name;
+        }
+
+        return $normalizedName;
+    }
+
     /**
      * Gets the default parameters.
      *
diff --git a/src/Symfony/Component/DependencyInjection/Tests/Fixtures/php/services_array_params.php b/src/Symfony/Component/DependencyInjection/Tests/Fixtures/php/services_array_params.php
index ff48181663..bf9e7c1dcf 100644
--- a/src/Symfony/Component/DependencyInjection/Tests/Fixtures/php/services_array_params.php
+++ b/src/Symfony/Component/DependencyInjection/Tests/Fixtures/php/services_array_params.php
@@ -86,7 +86,7 @@ class ProjectServiceContainer extends Container
     public function getParameter($name)
     {
         if (!(isset($this->parameters[$name]) || isset($this->loadedDynamicParameters[$name]) || array_key_exists($name, $this->parameters))) {
-            $name = strtolower($name);
+            $name = $this->normalizeParameterName($name);
 
             if (!(isset($this->parameters[$name]) || isset($this->loadedDynamicParameters[$name]) || array_key_exists($name, $this->parameters))) {
                 throw new InvalidArgumentException(sprintf('The parameter "%s" must be defined.', $name));
@@ -104,7 +104,7 @@ class ProjectServiceContainer extends Container
      */
     public function hasParameter($name)
     {
-        $name = strtolower($name);
+        $name = $this->normalizeParameterName($name);
 
         return isset($this->parameters[$name]) || isset($this->loadedDynamicParameters[$name]) || array_key_exists($name, $this->parameters);
     }
@@ -160,6 +160,22 @@ class ProjectServiceContainer extends Container
         return $this->dynamicParameters[$name] = $value;
     }
 
+    private $normalizedParameterNames = array();
+
+    private function normalizeParameterName($name)
+    {
+        if (isset($this->normalizedParameterNames[$normalizedName = strtolower($name)]) || isset($this->parameters[$normalizedName]) || array_key_exists($normalizedName, $this->parameters)) {
+            $normalizedName = isset($this->normalizedParameterNames[$normalizedName]) ? $this->normalizedParameterNames[$normalizedName] : $normalizedName;
+            if ((string) $name !== $normalizedName) {
+                @trigger_error(sprintf('Parameter names will be made case sensitive in Symfony 4.0. Using "%s" instead of "%s" is deprecated since version 3.4.', $name, $normalizedName), E_USER_DEPRECATED);
+            }
+        } else {
+            $normalizedName = $this->normalizedParameterNames[$normalizedName] = (string) $name;
+        }
+
+        return $normalizedName;
+    }
+
     /**
      * Gets the default parameters.
      *
diff --git a/src/Symfony/Component/DependencyInjection/Tests/Fixtures/xml/services2.xml b/src/Symfony/Component/DependencyInjection/Tests/Fixtures/xml/services2.xml
index f1ac14dd5d..0d2d669949 100644
--- a/src/Symfony/Component/DependencyInjection/Tests/Fixtures/xml/services2.xml
+++ b/src/Symfony/Component/DependencyInjection/Tests/Fixtures/xml/services2.xml
@@ -5,7 +5,7 @@
     xsi:schemaLocation="http://symfony.com/schema/dic/services http://symfony.com/schema/dic/services/services-1.0.xsd">
   <parameters>
     <parameter>a string</parameter>
-    <parameter key="FOO">bar</parameter>
+    <parameter key="foo">bar</parameter>
     <parameter key="values" type="collection">
       <parameter>0</parameter>
       <parameter key="integer">4</parameter>
@@ -23,7 +23,7 @@
         <parameter>bar</parameter>
       </parameter>
     </parameter>
-    <parameter key="MixedCase" type="collection"> <!-- Should be lower cased -->
+    <parameter key="mixedcase" type="collection"> <!-- Should be lower cased -->
       <parameter key="MixedCaseKey">value</parameter> <!-- Should stay mixed case -->
     </parameter>
     <parameter key="constant" type="constant">PHP_EOL</parameter>
diff --git a/src/Symfony/Component/DependencyInjection/Tests/Fixtures/yaml/services2.yml b/src/Symfony/Component/DependencyInjection/Tests/Fixtures/yaml/services2.yml
index 7ab302bcb9..e05d69d77e 100644
--- a/src/Symfony/Component/DependencyInjection/Tests/Fixtures/yaml/services2.yml
+++ b/src/Symfony/Component/DependencyInjection/Tests/Fixtures/yaml/services2.yml
@@ -1,5 +1,5 @@
 parameters:
-    FOO: bar
+    foo: bar
     values:
         - true
         - false
@@ -9,5 +9,5 @@ parameters:
     bar: foo
     escape: '@@escapeme'
     foo_bar: '@foo_bar'
-    MixedCase:
+    mixedcase:
         MixedCaseKey: value
diff --git a/src/Symfony/Component/DependencyInjection/Tests/ParameterBag/EnvPlaceholderParameterBagTest.php b/src/Symfony/Component/DependencyInjection/Tests/ParameterBag/EnvPlaceholderParameterBagTest.php
index 01fcd2c3ef..9abfb45d6e 100644
--- a/src/Symfony/Component/DependencyInjection/Tests/ParameterBag/EnvPlaceholderParameterBagTest.php
+++ b/src/Symfony/Component/DependencyInjection/Tests/ParameterBag/EnvPlaceholderParameterBagTest.php
@@ -115,18 +115,18 @@ class EnvPlaceholderParameterBagTest extends TestCase
     {
         $bag = new EnvPlaceholderParameterBag();
         $bag->get('env(INT_VAR)');
-        $bag->set('env(Int_Var)', 2);
+        $bag->set('env(INT_VAR)', 2);
         $bag->resolve();
-        $this->assertSame('2', $bag->all()['env(int_var)']);
+        $this->assertSame('2', $bag->all()['env(INT_VAR)']);
     }
 
     public function testResolveEnvAllowsNull()
     {
         $bag = new EnvPlaceholderParameterBag();
         $bag->get('env(NULL_VAR)');
-        $bag->set('env(Null_Var)', null);
+        $bag->set('env(NULL_VAR)', null);
         $bag->resolve();
-        $this->assertNull($bag->all()['env(null_var)']);
+        $this->assertNull($bag->all()['env(NULL_VAR)']);
     }
 
     /**
@@ -137,7 +137,7 @@ class EnvPlaceholderParameterBagTest extends TestCase
     {
         $bag = new EnvPlaceholderParameterBag();
         $bag->get('env(ARRAY_VAR)');
-        $bag->set('env(Array_Var)', array());
+        $bag->set('env(ARRAY_VAR)', array());
         $bag->resolve();
     }
 
@@ -148,7 +148,7 @@ class EnvPlaceholderParameterBagTest extends TestCase
         $bag->get('env(NULL_VAR)');
         $bag->resolve();
 
-        $this->assertNull($bag->all()['env(null_var)']);
+        $this->assertNull($bag->all()['env(NULL_VAR)']);
     }
 
     /**
diff --git a/src/Symfony/Component/DependencyInjection/Tests/ParameterBag/ParameterBagTest.php b/src/Symfony/Component/DependencyInjection/Tests/ParameterBag/ParameterBagTest.php
index 391e0eb3ff..3bac9ca64e 100644
--- a/src/Symfony/Component/DependencyInjection/Tests/ParameterBag/ParameterBagTest.php
+++ b/src/Symfony/Component/DependencyInjection/Tests/ParameterBag/ParameterBagTest.php
@@ -46,8 +46,6 @@ class ParameterBagTest extends TestCase
         ));
         $bag->remove('foo');
         $this->assertEquals(array('bar' => 'bar'), $bag->all(), '->remove() removes a parameter');
-        $bag->remove('BAR');
-        $this->assertEquals(array(), $bag->all(), '->remove() converts key to lowercase before removing');
     }
 
     public function testGetSet()
@@ -59,10 +57,6 @@ class ParameterBagTest extends TestCase
         $bag->set('foo', 'baz');
         $this->assertEquals('baz', $bag->get('foo'), '->set() overrides previously set parameter');
 
-        $bag->set('Foo', 'baz1');
-        $this->assertEquals('baz1', $bag->get('foo'), '->set() converts the key to lowercase');
-        $this->assertEquals('baz1', $bag->get('FOO'), '->get() converts the key to lowercase');
-
         try {
             $bag->get('baba');
             $this->fail('->get() throws an Symfony\Component\DependencyInjection\Exception\ParameterNotFoundException if the key does not exist');
@@ -109,10 +103,33 @@ class ParameterBagTest extends TestCase
     {
         $bag = new ParameterBag(array('foo' => 'bar'));
         $this->assertTrue($bag->has('foo'), '->has() returns true if a parameter is defined');
-        $this->assertTrue($bag->has('Foo'), '->has() converts the key to lowercase');
         $this->assertFalse($bag->has('bar'), '->has() returns false if a parameter is not defined');
     }
 
+    /**
+     * @group legacy
+     * @expectedDeprecation Parameter names will be made case sensitive in Symfony 4.0. Using "BAR" instead of "bar" is deprecated since version 3.4.
+     * @expectedDeprecation Parameter names will be made case sensitive in Symfony 4.0. Using "Foo" instead of "foo" is deprecated since version 3.4.
+     * @expectedDeprecation Parameter names will be made case sensitive in Symfony 4.0. Using "FOO" instead of "foo" is deprecated since version 3.4.
+     * @expectedDeprecation Parameter names will be made case sensitive in Symfony 4.0. Using "Foo" instead of "foo" is deprecated since version 3.4.
+     */
+    public function testMixedCase()
+    {
+        $bag = new ParameterBag(array(
+            'foo' => 'foo',
+            'bar' => 'bar',
+        ));
+
+        $bag->remove('BAR');
+        $this->assertEquals(array('foo' => 'foo'), $bag->all(), '->remove() converts key to lowercase before removing');
+
+        $bag->set('Foo', 'baz1');
+        $this->assertEquals('baz1', $bag->get('foo'), '->set() converts the key to lowercase');
+        $this->assertEquals('baz1', $bag->get('FOO'), '->get() converts the key to lowercase');
+
+        $this->assertTrue($bag->has('Foo'), '->has() converts the key to lowercase');
+    }
+
     public function testResolveValue()
     {
         $bag = new ParameterBag(array());
diff --git a/src/Symfony/Component/HttpFoundation/Session/Flash/AutoExpireFlashBag.php b/src/Symfony/Component/HttpFoundation/Session/Flash/AutoExpireFlashBag.php
index ddd603fdd1..138565aa31 100644
--- a/src/Symfony/Component/HttpFoundation/Session/Flash/AutoExpireFlashBag.php
+++ b/src/Symfony/Component/HttpFoundation/Session/Flash/AutoExpireFlashBag.php
@@ -39,7 +39,7 @@ class AutoExpireFlashBag implements FlashBagInterface
      *
      * @param string $storageKey The key used to store flashes in the session
      */
-    public function __construct($storageKey = '_sf2_flashes')
+    public function __construct($storageKey = '_symfony_flashes')
     {
         $this->storageKey = $storageKey;
     }
diff --git a/src/Symfony/Component/HttpFoundation/Session/Flash/FlashBag.php b/src/Symfony/Component/HttpFoundation/Session/Flash/FlashBag.php
index 85b4f00b00..ee6be434cc 100644
--- a/src/Symfony/Component/HttpFoundation/Session/Flash/FlashBag.php
+++ b/src/Symfony/Component/HttpFoundation/Session/Flash/FlashBag.php
@@ -39,7 +39,7 @@ class FlashBag implements FlashBagInterface
      *
      * @param string $storageKey The key used to store flashes in the session
      */
-    public function __construct($storageKey = '_sf2_flashes')
+    public function __construct($storageKey = '_symfony_flashes')
     {
         $this->storageKey = $storageKey;
     }
diff --git a/src/Symfony/Component/HttpFoundation/Tests/Session/Flash/AutoExpireFlashBagTest.php b/src/Symfony/Component/HttpFoundation/Tests/Session/Flash/AutoExpireFlashBagTest.php
index 4eb200afa3..c25befc4c3 100644
--- a/src/Symfony/Component/HttpFoundation/Tests/Session/Flash/AutoExpireFlashBagTest.php
+++ b/src/Symfony/Component/HttpFoundation/Tests/Session/Flash/AutoExpireFlashBagTest.php
@@ -62,7 +62,7 @@ class AutoExpireFlashBagTest extends TestCase
 
     public function testGetStorageKey()
     {
-        $this->assertEquals('_sf2_flashes', $this->bag->getStorageKey());
+        $this->assertEquals('_symfony_flashes', $this->bag->getStorageKey());
         $attributeBag = new FlashBag('test');
         $this->assertEquals('test', $attributeBag->getStorageKey());
     }
diff --git a/src/Symfony/Component/HttpFoundation/Tests/Session/Flash/FlashBagTest.php b/src/Symfony/Component/HttpFoundation/Tests/Session/Flash/FlashBagTest.php
index f0aa6a6157..07d1788807 100644
--- a/src/Symfony/Component/HttpFoundation/Tests/Session/Flash/FlashBagTest.php
+++ b/src/Symfony/Component/HttpFoundation/Tests/Session/Flash/FlashBagTest.php
@@ -57,7 +57,7 @@ class FlashBagTest extends TestCase
 
     public function testGetStorageKey()
     {
-        $this->assertEquals('_sf2_flashes', $this->bag->getStorageKey());
+        $this->assertEquals('_symfony_flashes', $this->bag->getStorageKey());
         $attributeBag = new FlashBag('test');
         $this->assertEquals('test', $attributeBag->getStorageKey());
     }
diff --git a/src/Symfony/Component/Translation/Command/XliffLintCommand.php b/src/Symfony/Component/Translation/Command/XliffLintCommand.php
index 80d8bb25dc..fead5edcb1 100644
--- a/src/Symfony/Component/Translation/Command/XliffLintCommand.php
+++ b/src/Symfony/Component/Translation/Command/XliffLintCommand.php
@@ -26,6 +26,8 @@ use Symfony\Component\Console\Style\SymfonyStyle;
  */
 class XliffLintCommand extends Command
 {
+    protected static $defaultName = 'lint:xliff';
+
     private $format;
     private $displayCorrectFiles;
     private $directoryIteratorProvider;
@@ -45,7 +47,6 @@ class XliffLintCommand extends Command
     protected function configure()
     {
         $this
-            ->setName('lint:xliff')
             ->setDescription('Lints a XLIFF file and outputs encountered errors')
             ->addArgument('filename', null, 'A file or a directory or STDIN')
             ->addOption('format', null, InputOption::VALUE_REQUIRED, 'The output format', 'txt')
diff --git a/src/Symfony/Component/Translation/Loader/XliffFileLoader.php b/src/Symfony/Component/Translation/Loader/XliffFileLoader.php
index e3cab65437..1603dc0b04 100644
--- a/src/Symfony/Component/Translation/Loader/XliffFileLoader.php
+++ b/src/Symfony/Component/Translation/Loader/XliffFileLoader.php
@@ -222,7 +222,7 @@ class XliffFileLoader implements LoaderInterface
         $newPath = str_replace('\\', '/', __DIR__).'/schema/dic/xliff-core/xml.xsd';
         $parts = explode('/', $newPath);
         if (0 === stripos($newPath, 'phar://')) {
-            $tmpfile = tempnam(sys_get_temp_dir(), 'sf2');
+            $tmpfile = tempnam(sys_get_temp_dir(), 'symfony');
             if ($tmpfile) {
                 copy($newPath, $tmpfile);
                 $parts = explode('/', str_replace('\\', '/', $tmpfile));
diff --git a/src/Symfony/Component/Yaml/Command/LintCommand.php b/src/Symfony/Component/Yaml/Command/LintCommand.php
index 36025bdebb..202291551b 100644
--- a/src/Symfony/Component/Yaml/Command/LintCommand.php
+++ b/src/Symfony/Component/Yaml/Command/LintCommand.php
@@ -28,6 +28,8 @@ use Symfony\Component\Yaml\Yaml;
  */
 class LintCommand extends Command
 {
+    protected static $defaultName = 'lint:yaml';
+
     private $parser;
     private $format;
     private $displayCorrectFiles;
@@ -48,7 +50,6 @@ class LintCommand extends Command
     protected function configure()
     {
         $this
-            ->setName('lint:yaml')
             ->setDescription('Lints a file and outputs encountered errors')
             ->addArgument('filename', null, 'A file or a directory or STDIN')
             ->addOption('format', null, InputOption::VALUE_REQUIRED, 'The output format', 'txt')
diff --git a/src/Symfony/Component/Yaml/composer.json b/src/Symfony/Component/Yaml/composer.json
index bbf8439349..7a34d82857 100644
--- a/src/Symfony/Component/Yaml/composer.json
+++ b/src/Symfony/Component/Yaml/composer.json
@@ -21,6 +21,9 @@
     "require-dev": {
         "symfony/console": "~3.4|~4.0"
     },
+    "conflict": {
+        "symfony/console": "<3.4"
+    },
     "suggest": {
         "symfony/console": "For validating YAML files using the lint command"
     },