diff --git a/src/Symfony/Bridge/PhpUnit/DeprecationErrorHandler.php b/src/Symfony/Bridge/PhpUnit/DeprecationErrorHandler.php
index ea426c377a..8ab5ee7a4b 100644
--- a/src/Symfony/Bridge/PhpUnit/DeprecationErrorHandler.php
+++ b/src/Symfony/Bridge/PhpUnit/DeprecationErrorHandler.php
@@ -96,7 +96,19 @@ class DeprecationErrorHandler
                 return \call_user_func(self::getPhpUnitErrorHandler(), $type, $msg, $file, $line, $context);
             }
 
-            $deprecations[] = [error_reporting(), $msg, $file];
+            $trace = debug_backtrace();
+            $filesStack = [];
+            foreach ($trace as $line) {
+                if (\in_array($line['function'], ['require', 'require_once', 'include', 'include_once'], true)) {
+                    continue;
+                }
+
+                if (isset($line['file'])) {
+                    $filesStack[] = $line['file'];
+                }
+            }
+
+            $deprecations[] = [error_reporting(), $msg, $file, $filesStack];
 
             return null;
         });
diff --git a/src/Symfony/Bridge/PhpUnit/DeprecationErrorHandler/Deprecation.php b/src/Symfony/Bridge/PhpUnit/DeprecationErrorHandler/Deprecation.php
index 6263267fef..55909ee6cf 100644
--- a/src/Symfony/Bridge/PhpUnit/DeprecationErrorHandler/Deprecation.php
+++ b/src/Symfony/Bridge/PhpUnit/DeprecationErrorHandler/Deprecation.php
@@ -44,6 +44,8 @@ class Deprecation
      */
     private static $internalPaths = [];
 
+    private $originalFilesStack;
+
     /**
      * @param string $message
      * @param string $file
@@ -64,6 +66,7 @@ class Deprecation
                 $this->message = $parsedMsg['deprecation'];
                 $this->originClass = $parsedMsg['class'];
                 $this->originMethod = $parsedMsg['method'];
+                $this->originalFilesStack = $parsedMsg['files_stack'];
                 // If the deprecation has been triggered via
                 // \Symfony\Bridge\PhpUnit\Legacy\SymfonyTestsListenerTrait::endTest()
                 // then we need to use the serialized information to determine
@@ -162,6 +165,24 @@ class Deprecation
         return false !== strpos($this->triggeringFile, \DIRECTORY_SEPARATOR.'vendor'.\DIRECTORY_SEPARATOR.'phpunit'.\DIRECTORY_SEPARATOR);
     }
 
+    private function getOriginalFilesStack(): array
+    {
+        if (null === $this->originalFilesStack) {
+            $this->originalFilesStack = [];
+            foreach ($this->trace as $line) {
+                if (\in_array($line['function'], ['require', 'require_once', 'include', 'include_once'], true)) {
+                    continue;
+                }
+                if (!isset($line['file'])) {
+                    continue;
+                }
+                $this->originalFilesStack[] = $line['file'];
+            }
+        }
+
+        return $this->originalFilesStack;
+    }
+
     /**
      * Tells whether both the calling package and the called package are vendor
      * packages.
@@ -178,14 +199,8 @@ class Deprecation
             return self::TYPE_UNDETERMINED;
         }
         $erroringFile = $erroringPackage = null;
-        foreach ($this->trace as $line) {
-            if (\in_array($line['function'], ['require', 'require_once', 'include', 'include_once'], true)) {
-                continue;
-            }
-            if (!isset($line['file'])) {
-                continue;
-            }
-            $file = $line['file'];
+
+        foreach ($this->getOriginalFilesStack() as $file) {
             if ('-' === $file || 'Standard input code' === $file || !realpath($file)) {
                 continue;
             }
diff --git a/src/Symfony/Bridge/PhpUnit/Tests/DeprecationErrorHandler/DeprecationTest.php b/src/Symfony/Bridge/PhpUnit/Tests/DeprecationErrorHandler/DeprecationTest.php
index d59b2d9337..af3f688d5d 100644
--- a/src/Symfony/Bridge/PhpUnit/Tests/DeprecationErrorHandler/DeprecationTest.php
+++ b/src/Symfony/Bridge/PhpUnit/Tests/DeprecationErrorHandler/DeprecationTest.php
@@ -11,12 +11,32 @@
 
 namespace Symfony\Bridge\PhpUnit\Tests\DeprecationErrorHandler;
 
+use Composer\Autoload\ClassLoader;
 use PHPUnit\Framework\TestCase;
 use Symfony\Bridge\PhpUnit\DeprecationErrorHandler;
 use Symfony\Bridge\PhpUnit\DeprecationErrorHandler\Deprecation;
+use Symfony\Bridge\PhpUnit\Legacy\SymfonyTestsListenerForV5;
 
 class DeprecationTest extends TestCase
 {
+    public static function setUpBeforeClass(): void
+    {
+        $vendorDir = self::getVendorDir();
+
+        mkdir($vendorDir.'/myfakevendor/myfakepackage1', 0777, true);
+        mkdir($vendorDir.'/myfakevendor/myfakepackage2');
+        touch($vendorDir.'/myfakevendor/myfakepackage1/MyFakeFile1.php');
+        touch($vendorDir.'/myfakevendor/myfakepackage1/MyFakeFile2.php');
+        touch($vendorDir.'/myfakevendor/myfakepackage2/MyFakeFile.php');
+    }
+
+    private static function getVendorDir(): string
+    {
+        $reflection = new \ReflectionClass(ClassLoader::class);
+
+        return \dirname($reflection->getFileName(), 2);
+    }
+
     public function testItCanDetermineTheClassWhereTheDeprecationHappened()
     {
         $deprecation = new Deprecation('💩', $this->debugBacktrace(), __FILE__);
@@ -118,12 +138,135 @@ class DeprecationTest extends TestCase
         $this->assertTrue($deprecation->isMuted());
     }
 
+    public function providerGetTypeDetectsSelf(): array
+    {
+        foreach (get_declared_classes() as $class) {
+            if ('C' === $class[0] && 0 === strpos($class, 'ComposerAutoloaderInit')) {
+                $r = new \ReflectionClass($class);
+                $v = \dirname(\dirname($r->getFileName()));
+                if (file_exists($v.'/composer/installed.json')) {
+                    $loader = require $v.'/autoload.php';
+                    $reflection = new \ReflectionClass($loader);
+                    $prop = $reflection->getProperty('prefixDirsPsr4');
+                    $prop->setAccessible(true);
+                    $currentValue = $prop->getValue($loader);
+                    $currentValue['Symfony\\Bridge\\PhpUnit\\'] = [realpath(__DIR__.'/../..')];
+                    $prop->setValue($loader, $currentValue);
+                }
+            }
+        }
+
+        return [
+            'not_from_vendors_file' => [Deprecation::TYPE_SELF, '', 'MyClass1', ''],
+            'nonexistent_file' => [Deprecation::TYPE_UNDETERMINED, '', 'MyClass1', 'dummy_vendor_path'],
+            'serialized_trace_with_nonexistent_triggering_file' => [
+                Deprecation::TYPE_UNDETERMINED,
+                serialize([
+                    'class' => '',
+                    'method' => '',
+                    'deprecation' => '',
+                    'triggering_file' => 'dummy_vendor_path',
+                    'files_stack' => [],
+                ]),
+                SymfonyTestsListenerForV5::class,
+                '',
+            ],
+        ];
+    }
+
+    /**
+     * @dataProvider providerGetTypeDetectsSelf
+     */
+    public function testGetTypeDetectsSelf(string $expectedType, string $message, string $traceClass, string $file): void
+    {
+        $trace = [
+            ['class' => 'MyClass1', 'function' => 'myMethod'],
+            ['class' => $traceClass, 'function' => 'myMethod'],
+        ];
+        $deprecation = new Deprecation($message, $trace, $file);
+        $this->assertEquals($expectedType, $deprecation->getType());
+    }
+
+    public function providerGetTypeUsesRightTrace(): array
+    {
+        $vendorDir = self::getVendorDir();
+
+        return [
+            'no_file_in_stack' => [Deprecation::TYPE_DIRECT, '', [['function' => 'myfunc1'], ['function' => 'myfunc2']]],
+            'files_in_stack_from_various_packages' => [
+                Deprecation::TYPE_INDIRECT,
+                '',
+                [
+                    ['function' => 'myfunc1', 'file' => $vendorDir.'/myfakevendor/myfakepackage1/MyFakeFile1.php'],
+                    ['function' => 'myfunc2', 'file' => $vendorDir.'/myfakevendor/myfakepackage2/MyFakeFile.php'],
+                ],
+            ],
+            'serialized_stack_files_from_same_package' => [
+                Deprecation::TYPE_DIRECT,
+                serialize([
+                    'deprecation' => 'My deprecation message',
+                    'class' => 'MyClass',
+                    'method' => 'myMethod',
+                    'files_stack' => [
+                        $vendorDir.'/myfakevendor/myfakepackage1/MyFakeFile1.php',
+                        $vendorDir.'/myfakevendor/myfakepackage1/MyFakeFile2.php',
+                    ],
+                ]),
+                [['function' => 'myfunc1'], ['class' => SymfonyTestsListenerForV5::class, 'method' => 'mymethod']],
+            ],
+            'serialized_stack_files_from_various_packages' => [
+                Deprecation::TYPE_INDIRECT,
+                serialize([
+                    'deprecation' => 'My deprecation message',
+                    'class' => 'MyClass',
+                    'method' => 'myMethod',
+                    'files_stack' => [
+                        $vendorDir.'/myfakevendor/myfakepackage1/MyFakeFile1.php',
+                        $vendorDir.'/myfakevendor/myfakepackage2/MyFakeFile.php',
+                    ],
+                ]),
+                [['function' => 'myfunc1'], ['class' => SymfonyTestsListenerForV5::class, 'method' => 'mymethod']],
+            ],
+        ];
+    }
+
+    /**
+     * @dataProvider providerGetTypeUsesRightTrace
+     */
+    public function testGetTypeUsesRightTrace(string $expectedType, string $message, array $trace): void
+    {
+        $deprecation = new Deprecation(
+            $message,
+            $trace,
+            self::getVendorDir().'/myfakevendor/myfakepackage2/MyFakeFile.php'
+        );
+        $this->assertEquals($expectedType, $deprecation->getType());
+    }
+
     /**
      * This method is here to simulate the extra level from the piece of code
-     * triggering an error to the error handler
+     * triggering an error to the error handler.
      */
     public function debugBacktrace(): array
     {
         return debug_backtrace();
     }
+
+    private static function removeDir($dir): void
+    {
+        $files = glob($dir.'/*');
+        foreach ($files as $file) {
+            if (is_file($file)) {
+                unlink($file);
+            } else {
+                self::removeDir($file);
+            }
+        }
+        rmdir($dir);
+    }
+
+    public static function tearDownAfterClass(): void
+    {
+        self::removeDir(self::getVendorDir().'/myfakevendor');
+    }
 }
diff --git a/src/Symfony/Bundle/FrameworkBundle/DependencyInjection/Configuration.php b/src/Symfony/Bundle/FrameworkBundle/DependencyInjection/Configuration.php
index 65cf6e5599..1632956f7e 100644
--- a/src/Symfony/Bundle/FrameworkBundle/DependencyInjection/Configuration.php
+++ b/src/Symfony/Bundle/FrameworkBundle/DependencyInjection/Configuration.php
@@ -1279,7 +1279,7 @@ class Configuration implements ConfigurationInterface
                                             if (!\is_array($config)) {
                                                 return [];
                                             }
-                                            if (!isset($config['host'])) {
+                                            if (!isset($config['host'], $config['value']) || \count($config) > 2) {
                                                 return $config;
                                             }
 
@@ -1388,7 +1388,7 @@ class Configuration implements ConfigurationInterface
                                                 if (!\is_array($config)) {
                                                     return [];
                                                 }
-                                                if (!isset($config['key'])) {
+                                                if (!isset($config['key'], $config['value']) || \count($config) > 2) {
                                                     return $config;
                                                 }
 
@@ -1418,7 +1418,7 @@ class Configuration implements ConfigurationInterface
                                                 if (!\is_array($config)) {
                                                     return [];
                                                 }
-                                                if (!isset($config['host'])) {
+                                                if (!isset($config['host'], $config['value']) || \count($config) > 2) {
                                                     return $config;
                                                 }
 
diff --git a/src/Symfony/Bundle/FrameworkBundle/Tests/DependencyInjection/Fixtures/php/http_client_xml_key.php b/src/Symfony/Bundle/FrameworkBundle/Tests/DependencyInjection/Fixtures/php/http_client_xml_key.php
new file mode 100644
index 0000000000..64778c6156
--- /dev/null
+++ b/src/Symfony/Bundle/FrameworkBundle/Tests/DependencyInjection/Fixtures/php/http_client_xml_key.php
@@ -0,0 +1,22 @@
+<?php
+
+$container->loadFromExtension('framework', [
+    'http_client' => [
+        'default_options' => [
+            'resolve' => [
+                'host' => '127.0.0.1',
+            ],
+        ],
+        'scoped_clients' => [
+            'foo' => [
+                'base_uri' => 'http://example.com',
+                'query' => [
+                    'key' => 'foo',
+                ],
+                'resolve' => [
+                    'host' => '127.0.0.1',
+                ],
+            ],
+        ],
+    ],
+]);
diff --git a/src/Symfony/Bundle/FrameworkBundle/Tests/DependencyInjection/Fixtures/xml/http_client_xml_key.xml b/src/Symfony/Bundle/FrameworkBundle/Tests/DependencyInjection/Fixtures/xml/http_client_xml_key.xml
new file mode 100644
index 0000000000..95ef0737f8
--- /dev/null
+++ b/src/Symfony/Bundle/FrameworkBundle/Tests/DependencyInjection/Fixtures/xml/http_client_xml_key.xml
@@ -0,0 +1,19 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<container xmlns="http://symfony.com/schema/dic/services"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xmlns:framework="http://symfony.com/schema/dic/symfony"
+    xsi:schemaLocation="http://symfony.com/schema/dic/services http://symfony.com/schema/dic/services/services-1.0.xsd
+        http://symfony.com/schema/dic/symfony http://symfony.com/schema/dic/symfony/symfony-1.0.xsd">
+
+    <framework:config>
+        <framework:http-client>
+            <framework:default-options>
+                <framework:resolve host="host">127.0.0.1</framework:resolve>
+            </framework:default-options>
+            <framework:scoped-client name="foo" base-uri="http://example.com">
+                <framework:query key="key">foo</framework:query>
+                <framework:resolve host="host">127.0.0.1</framework:resolve>
+            </framework:scoped-client>
+        </framework:http-client>
+    </framework:config>
+</container>
diff --git a/src/Symfony/Bundle/FrameworkBundle/Tests/DependencyInjection/Fixtures/yml/http_client_xml_key.yml b/src/Symfony/Bundle/FrameworkBundle/Tests/DependencyInjection/Fixtures/yml/http_client_xml_key.yml
new file mode 100644
index 0000000000..dc87555a90
--- /dev/null
+++ b/src/Symfony/Bundle/FrameworkBundle/Tests/DependencyInjection/Fixtures/yml/http_client_xml_key.yml
@@ -0,0 +1,12 @@
+framework:
+    http_client:
+        default_options:
+            resolve:
+                host: 127.0.0.1
+        scoped_clients:
+            foo:
+                base_uri: http://example.com
+                query:
+                    key: foo
+                resolve:
+                    host: 127.0.0.1
diff --git a/src/Symfony/Bundle/FrameworkBundle/Tests/DependencyInjection/FrameworkExtensionTest.php b/src/Symfony/Bundle/FrameworkBundle/Tests/DependencyInjection/FrameworkExtensionTest.php
index 7ac19bcd18..86b3fae486 100644
--- a/src/Symfony/Bundle/FrameworkBundle/Tests/DependencyInjection/FrameworkExtensionTest.php
+++ b/src/Symfony/Bundle/FrameworkBundle/Tests/DependencyInjection/FrameworkExtensionTest.php
@@ -1360,6 +1360,21 @@ abstract class FrameworkExtensionTest extends TestCase
         $this->assertSame($expected, $container->getDefinition('foo')->getArgument(2));
     }
 
+    public function testHttpClientWithQueryParameterKey()
+    {
+        $container = $this->createContainerFromFile('http_client_xml_key');
+
+        $expected = [
+            'key' => 'foo',
+        ];
+        $this->assertSame($expected, $container->getDefinition('foo')->getArgument(2)['query']);
+
+        $expected = [
+            'host' => '127.0.0.1',
+        ];
+        $this->assertSame($expected, $container->getDefinition('foo')->getArgument(2)['resolve']);
+    }
+
     public function testHttpClientFullDefaultOptions()
     {
         $container = $this->createContainerFromFile('http_client_full_default_options');
diff --git a/src/Symfony/Component/DependencyInjection/Compiler/PriorityTaggedServiceTrait.php b/src/Symfony/Component/DependencyInjection/Compiler/PriorityTaggedServiceTrait.php
index 9b3760b497..1a2c829854 100644
--- a/src/Symfony/Component/DependencyInjection/Compiler/PriorityTaggedServiceTrait.php
+++ b/src/Symfony/Component/DependencyInjection/Compiler/PriorityTaggedServiceTrait.php
@@ -54,78 +54,81 @@ trait PriorityTaggedServiceTrait
 
         foreach ($container->findTaggedServiceIds($tagName, true) as $serviceId => $attributes) {
             $class = $r = null;
-            $priority = 0;
-            if (isset($attributes[0]['priority'])) {
-                $priority = $attributes[0]['priority'];
-            } elseif ($defaultPriorityMethod) {
-                $class = $container->getDefinition($serviceId)->getClass();
-                $class = $container->getParameterBag()->resolveValue($class) ?: null;
 
-                if (($r = $container->getReflectionClass($class)) && $r->hasMethod($defaultPriorityMethod)) {
-                    if (!($rm = $r->getMethod($defaultPriorityMethod))->isStatic()) {
-                        throw new InvalidArgumentException(sprintf('Method "%s::%s()" should be static: tag "%s" on service "%s".', $class, $defaultPriorityMethod, $tagName, $serviceId));
-                    }
+            $defaultPriority = null;
+            $defaultIndex = null;
 
-                    if (!$rm->isPublic()) {
-                        throw new InvalidArgumentException(sprintf('Method "%s::%s()" should be public: tag "%s" on service "%s".', $class, $defaultPriorityMethod, $tagName, $serviceId));
-                    }
+            foreach ($attributes as $attribute) {
+                $index = $priority = null;
 
-                    $priority = $rm->invoke(null);
+                if (isset($attribute['priority'])) {
+                    $priority = $attribute['priority'];
+                } elseif (null === $defaultPriority && $defaultPriorityMethod) {
+                    $class = $container->getDefinition($serviceId)->getClass();
+                    $class = $container->getParameterBag()->resolveValue($class) ?: null;
 
-                    if (!\is_int($priority)) {
-                        throw new InvalidArgumentException(sprintf('Method "%s::%s()" should return an integer, got %s: tag "%s" on service "%s".', $class, $defaultPriorityMethod, \gettype($priority), $tagName, $serviceId));
+                    if (($r = ($r ?? $container->getReflectionClass($class))) && $r->hasMethod($defaultPriorityMethod)) {
+                        if (!($rm = $r->getMethod($defaultPriorityMethod))->isStatic()) {
+                            throw new InvalidArgumentException(sprintf('Method "%s::%s()" should be static: tag "%s" on service "%s".', $class, $defaultPriorityMethod, $tagName, $serviceId));
+                        }
+
+                        if (!$rm->isPublic()) {
+                            throw new InvalidArgumentException(sprintf('Method "%s::%s()" should be public: tag "%s" on service "%s".', $class, $defaultPriorityMethod, $tagName, $serviceId));
+                        }
+
+                        $defaultPriority = $rm->invoke(null);
+
+                        if (!\is_int($defaultPriority)) {
+                            throw new InvalidArgumentException(sprintf('Method "%s::%s()" should return an integer, got %s: tag "%s" on service "%s".', $class, $defaultPriorityMethod, \gettype($priority), $tagName, $serviceId));
+                        }
                     }
                 }
-            }
 
-            if (null === $indexAttribute && !$needsIndexes) {
-                $services[$priority][] = new Reference($serviceId);
+                $priority = $priority ?? $defaultPriority ?? 0;
 
-                continue;
-            }
+                if (null !== $indexAttribute && isset($attribute[$indexAttribute])) {
+                    $index = $attribute[$indexAttribute];
+                } elseif (null === $defaultIndex && null === $indexAttribute && !$needsIndexes) {
+                    // With partially associative array, insertion to get next key is simpler.
+                    $services[$priority][] = null;
+                    end($services[$priority]);
+                    $defaultIndex = key($services[$priority]);
+                } elseif (null === $defaultIndex && $defaultIndexMethod) {
+                    $class = $container->getDefinition($serviceId)->getClass();
+                    $class = $container->getParameterBag()->resolveValue($class) ?: null;
 
-            if (!$class) {
-                $class = $container->getDefinition($serviceId)->getClass();
-                $class = $container->getParameterBag()->resolveValue($class) ?: null;
-            }
+                    if (($r = ($r ?? $container->getReflectionClass($class))) && $r->hasMethod($defaultIndexMethod)) {
+                        if (!($rm = $r->getMethod($defaultIndexMethod))->isStatic()) {
+                            throw new InvalidArgumentException(sprintf('Method "%s::%s()" should be static: tag "%s" on service "%s" is missing "%s" attribute.', $class, $defaultIndexMethod, $tagName, $serviceId, $indexAttribute));
+                        }
 
-            if (null !== $indexAttribute && isset($attributes[0][$indexAttribute])) {
-                $services[$priority][$attributes[0][$indexAttribute]] = new TypedReference($serviceId, $class, ContainerBuilder::EXCEPTION_ON_INVALID_REFERENCE, $attributes[0][$indexAttribute]);
+                        if (!$rm->isPublic()) {
+                            throw new InvalidArgumentException(sprintf('Method "%s::%s()" should be public: tag "%s" on service "%s" is missing "%s" attribute.', $class, $defaultIndexMethod, $tagName, $serviceId, $indexAttribute));
+                        }
 
-                continue;
-            }
+                        $defaultIndex = $rm->invoke(null);
 
-            if (!$r && !$r = $container->getReflectionClass($class)) {
-                throw new InvalidArgumentException(sprintf('Class "%s" used for service "%s" cannot be found.', $class, $serviceId));
-            }
+                        if (!\is_string($defaultIndex)) {
+                            throw new InvalidArgumentException(sprintf('Method "%s::%s()" should return a string, got %s: tag "%s" on service "%s" is missing "%s" attribute.', $class, $defaultIndexMethod, \gettype($defaultIndex), $tagName, $serviceId, $indexAttribute));
+                        }
+                    }
 
-            $class = $r->name;
-
-            if (!$r->hasMethod($defaultIndexMethod)) {
-                if ($needsIndexes) {
-                    $services[$priority][$serviceId] = new TypedReference($serviceId, $class);
-
-                    continue;
+                    $defaultIndex = $defaultIndex ?? $serviceId;
                 }
 
-                throw new InvalidArgumentException(sprintf('Method "%s::%s()" not found: tag "%s" on service "%s" is missing "%s" attribute.', $class, $defaultIndexMethod, $tagName, $serviceId, $indexAttribute));
+                $index = $index ?? $defaultIndex;
+
+                $reference = null;
+                if (!$class || 'stdClass' === $class) {
+                    $reference = new Reference($serviceId);
+                } elseif ($index === $serviceId) {
+                    $reference = new TypedReference($serviceId, $class);
+                } else {
+                    $reference = new TypedReference($serviceId, $class, ContainerBuilder::EXCEPTION_ON_INVALID_REFERENCE, \is_string($index) ? $index : null);
+                }
+
+                $services[$priority][$index] = $reference;
             }
-
-            if (!($rm = $r->getMethod($defaultIndexMethod))->isStatic()) {
-                throw new InvalidArgumentException(sprintf('Method "%s::%s()" should be static: tag "%s" on service "%s" is missing "%s" attribute.', $class, $defaultIndexMethod, $tagName, $serviceId, $indexAttribute));
-            }
-
-            if (!$rm->isPublic()) {
-                throw new InvalidArgumentException(sprintf('Method "%s::%s()" should be public: tag "%s" on service "%s" is missing "%s" attribute.', $class, $defaultIndexMethod, $tagName, $serviceId, $indexAttribute));
-            }
-
-            $key = $rm->invoke(null);
-
-            if (!\is_string($key)) {
-                throw new InvalidArgumentException(sprintf('Method "%s::%s()" should return a string, got %s: tag "%s" on service "%s" is missing "%s" attribute.', $class, $defaultIndexMethod, \gettype($key), $tagName, $serviceId, $indexAttribute));
-            }
-
-            $services[$priority][$key] = new TypedReference($serviceId, $class, ContainerBuilder::EXCEPTION_ON_INVALID_REFERENCE, $key);
         }
 
         if ($services) {
diff --git a/src/Symfony/Component/DependencyInjection/EnvVarProcessor.php b/src/Symfony/Component/DependencyInjection/EnvVarProcessor.php
index bd25e3f0ec..987605f98f 100644
--- a/src/Symfony/Component/DependencyInjection/EnvVarProcessor.php
+++ b/src/Symfony/Component/DependencyInjection/EnvVarProcessor.php
@@ -126,9 +126,7 @@ class EnvVarProcessor implements EnvVarProcessorInterface
         }
 
         if (false !== $i || 'string' !== $prefix) {
-            if (null === $env = $getEnv($name)) {
-                return null;
-            }
+            $env = $getEnv($name);
         } elseif (isset($_ENV[$name])) {
             $env = $_ENV[$name];
         } elseif (isset($_SERVER[$name]) && 0 !== strpos($name, 'HTTP_')) {
@@ -173,12 +171,18 @@ class EnvVarProcessor implements EnvVarProcessorInterface
                     throw new EnvNotFoundException(sprintf('Environment variable not found: "%s".', $name));
                 }
 
-                if (null === $env = $this->container->getParameter("env($name)")) {
-                    return null;
-                }
+                $env = $this->container->getParameter("env($name)");
             }
         }
 
+        if (null === $env) {
+            if (!isset($this->getProvidedTypes()[$prefix])) {
+                throw new RuntimeException(sprintf('Unsupported env var prefix "%s".', $prefix));
+            }
+
+            return null;
+        }
+
         if (!is_scalar($env)) {
             throw new RuntimeException(sprintf('Non-scalar env var "%s" cannot be cast to %s.', $name, $prefix));
         }
diff --git a/src/Symfony/Component/DependencyInjection/Tests/Compiler/IntegrationTest.php b/src/Symfony/Component/DependencyInjection/Tests/Compiler/IntegrationTest.php
index 7d4f01a265..f6c255484a 100644
--- a/src/Symfony/Component/DependencyInjection/Tests/Compiler/IntegrationTest.php
+++ b/src/Symfony/Component/DependencyInjection/Tests/Compiler/IntegrationTest.php
@@ -314,6 +314,32 @@ class IntegrationTest extends TestCase
         $this->assertSame(['bar_tab_class_with_defaultmethod' => $container->get(BarTagClass::class), 'foo' => $container->get(FooTagClass::class)], $param);
     }
 
+    public function testTaggedIteratorWithMultipleIndexAttribute()
+    {
+        $container = new ContainerBuilder();
+        $container->register(BarTagClass::class)
+            ->setPublic(true)
+            ->addTag('foo_bar', ['foo' => 'bar'])
+            ->addTag('foo_bar', ['foo' => 'bar_duplicate'])
+        ;
+        $container->register(FooTagClass::class)
+            ->setPublic(true)
+            ->addTag('foo_bar')
+            ->addTag('foo_bar')
+        ;
+        $container->register(FooBarTaggedClass::class)
+            ->addArgument(new TaggedIteratorArgument('foo_bar', 'foo'))
+            ->setPublic(true)
+        ;
+
+        $container->compile();
+
+        $s = $container->get(FooBarTaggedClass::class);
+
+        $param = iterator_to_array($s->getParam()->getIterator());
+        $this->assertSame(['bar' => $container->get(BarTagClass::class), 'bar_duplicate' => $container->get(BarTagClass::class), 'foo_tag_class' => $container->get(FooTagClass::class)], $param);
+    }
+
     public function testTaggedServiceWithDefaultPriorityMethod()
     {
         $container = new ContainerBuilder();
@@ -350,7 +376,7 @@ class IntegrationTest extends TestCase
             ->addTag('foo_bar')
         ;
         $container->register('foo_bar_tagged', FooBarTaggedClass::class)
-            ->addArgument(new ServiceLocatorArgument(new TaggedIteratorArgument('foo_bar', 'foo')))
+            ->addArgument(new ServiceLocatorArgument(new TaggedIteratorArgument('foo_bar', 'foo', null, true)))
             ->setPublic(true)
         ;
 
@@ -369,6 +395,40 @@ class IntegrationTest extends TestCase
         $this->assertSame(['bar' => $container->get('bar_tag'), 'foo_tag_class' => $container->get('foo_tag')], $same);
     }
 
+    public function testTaggedServiceLocatorWithMultipleIndexAttribute()
+    {
+        $container = new ContainerBuilder();
+        $container->register('bar_tag', BarTagClass::class)
+            ->setPublic(true)
+            ->addTag('foo_bar', ['foo' => 'bar'])
+            ->addTag('foo_bar', ['foo' => 'bar_duplicate'])
+        ;
+        $container->register('foo_tag', FooTagClass::class)
+            ->setPublic(true)
+            ->addTag('foo_bar')
+            ->addTag('foo_bar')
+        ;
+        $container->register('foo_bar_tagged', FooBarTaggedClass::class)
+            ->addArgument(new ServiceLocatorArgument(new TaggedIteratorArgument('foo_bar', 'foo', null, true)))
+            ->setPublic(true)
+        ;
+
+        $container->compile();
+
+        $s = $container->get('foo_bar_tagged');
+
+        /** @var ServiceLocator $serviceLocator */
+        $serviceLocator = $s->getParam();
+        $this->assertTrue($s->getParam() instanceof ServiceLocator, sprintf('Wrong instance, should be an instance of ServiceLocator, %s given', \is_object($serviceLocator) ? \get_class($serviceLocator) : \gettype($serviceLocator)));
+
+        $same = [
+            'bar' => $serviceLocator->get('bar'),
+            'bar_duplicate' => $serviceLocator->get('bar_duplicate'),
+            'foo_tag_class' => $serviceLocator->get('foo_tag_class'),
+        ];
+        $this->assertSame(['bar' => $container->get('bar_tag'), 'bar_duplicate' => $container->get('bar_tag'), 'foo_tag_class' => $container->get('foo_tag')], $same);
+    }
+
     public function testTaggedServiceLocatorWithIndexAttributeAndDefaultMethod()
     {
         $container = new ContainerBuilder();
@@ -381,7 +441,7 @@ class IntegrationTest extends TestCase
             ->addTag('foo_bar', ['foo' => 'foo'])
         ;
         $container->register('foo_bar_tagged', FooBarTaggedClass::class)
-            ->addArgument(new ServiceLocatorArgument(new TaggedIteratorArgument('foo_bar', 'foo', 'getFooBar')))
+            ->addArgument(new ServiceLocatorArgument(new TaggedIteratorArgument('foo_bar', 'foo', 'getFooBar', true)))
             ->setPublic(true)
         ;
 
diff --git a/src/Symfony/Component/DependencyInjection/Tests/EnvVarProcessorTest.php b/src/Symfony/Component/DependencyInjection/Tests/EnvVarProcessorTest.php
index df329b4f7e..313bce5973 100644
--- a/src/Symfony/Component/DependencyInjection/Tests/EnvVarProcessorTest.php
+++ b/src/Symfony/Component/DependencyInjection/Tests/EnvVarProcessorTest.php
@@ -9,6 +9,7 @@ use Symfony\Component\DependencyInjection\ContainerBuilder;
 use Symfony\Component\DependencyInjection\EnvVarLoaderInterface;
 use Symfony\Component\DependencyInjection\EnvVarProcessor;
 use Symfony\Component\DependencyInjection\Exception\ParameterCircularReferenceException;
+use Symfony\Component\DependencyInjection\Exception\RuntimeException;
 
 class EnvVarProcessorTest extends TestCase
 {
@@ -595,4 +596,17 @@ CSV;
 
         $this->assertSame(2, $index);
     }
+
+    public function testGetEnvInvalidPrefixWithDefault()
+    {
+        $this->expectException(RuntimeException::class);
+        $this->expectExceptionMessage('Unsupported env var prefix');
+        $processor = new EnvVarProcessor(new Container());
+
+        $processor->getEnv('unknown', 'default::FAKE', function ($name) {
+            $this->assertSame('default::FAKE', $name);
+
+            return null;
+        });
+    }
 }
diff --git a/src/Symfony/Component/Mailer/Bridge/Mailchimp/Http/MandrillTransport.php b/src/Symfony/Component/Mailer/Bridge/Mailchimp/Http/MandrillTransport.php
index b6b3bef07e..79201f7f8a 100644
--- a/src/Symfony/Component/Mailer/Bridge/Mailchimp/Http/MandrillTransport.php
+++ b/src/Symfony/Component/Mailer/Bridge/Mailchimp/Http/MandrillTransport.php
@@ -16,7 +16,7 @@ use Symfony\Component\EventDispatcher\EventDispatcherInterface;
 use Symfony\Component\Mailer\Exception\TransportException;
 use Symfony\Component\Mailer\SentMessage;
 use Symfony\Component\Mailer\SmtpEnvelope;
-use Symfony\Component\Mailer\Transport\Http\AbstractHttpTransport;
+use Symfony\Component\Mailer\Transport\AbstractHttpTransport;
 use Symfony\Component\Mime\Address;
 use Symfony\Contracts\HttpClient\HttpClientInterface;
 
diff --git a/src/Symfony/Component/Mailer/Bridge/Mailchimp/Transport/MandrillHttpTransport.php b/src/Symfony/Component/Mailer/Bridge/Mailchimp/Transport/MandrillHttpTransport.php
index c40899c0d9..f401198313 100644
--- a/src/Symfony/Component/Mailer/Bridge/Mailchimp/Transport/MandrillHttpTransport.php
+++ b/src/Symfony/Component/Mailer/Bridge/Mailchimp/Transport/MandrillHttpTransport.php
@@ -49,7 +49,9 @@ class MandrillHttpTransport extends AbstractHttpTransport
         $response = $this->client->request('POST', 'https://'.$this->getEndpoint().'/api/1.0/messages/send-raw.json', [
             'json' => [
                 'key' => $this->key,
-                'to' => $this->getRecipients($envelope),
+                'to' => array_map(function (Address $recipient): string {
+                    return $recipient->getAddress();
+                }, $envelope->getRecipients()),
                 'from_email' => $envelope->getSender()->toString(),
                 'raw_message' => $message->toString(),
             ],
@@ -73,14 +75,4 @@ class MandrillHttpTransport extends AbstractHttpTransport
     {
         return ($this->host ?: self::HOST).($this->port ? ':'.$this->port : '');
     }
-
-    /**
-     * @return string[]
-     */
-    private function getRecipients(Envelope $envelope): array
-    {
-        return array_map(function (Address $recipient): string {
-            return $recipient->getAddress();
-        }, $envelope->getRecipients());
-    }
 }