diff --git a/src/Symfony/Bridge/PhpUnit/bin/simple-phpunit.php b/src/Symfony/Bridge/PhpUnit/bin/simple-phpunit.php
index dac9a897ee..a9dcfd50ba 100644
--- a/src/Symfony/Bridge/PhpUnit/bin/simple-phpunit.php
+++ b/src/Symfony/Bridge/PhpUnit/bin/simple-phpunit.php
@@ -53,6 +53,14 @@ $getEnvVar = function ($name, $default = false) use ($argv) {
     return $default;
 };
 
+$passthruOrFail = function ($command) {
+    passthru($command, $status);
+
+    if ($status) {
+        exit($status);
+    }
+};
+
 if (PHP_VERSION_ID >= 70200) {
     // PHPUnit 8 requires PHP 7.2+
     $PHPUNIT_VERSION = $getEnvVar('SYMFONY_PHPUNIT_VERSION', '8.3');
@@ -63,9 +71,10 @@ if (PHP_VERSION_ID >= 70200) {
     // PHPUnit 6 requires PHP 7.0+
     $PHPUNIT_VERSION = $getEnvVar('SYMFONY_PHPUNIT_VERSION', '6.5');
 } elseif (PHP_VERSION_ID >= 50600) {
-    // PHPUnit 5 requires PHP 5.6+
+    // PHPUnit 4 does not support PHP 7
     $PHPUNIT_VERSION = $getEnvVar('SYMFONY_PHPUNIT_VERSION', '5.7');
 } else {
+    // PHPUnit 5.1 requires PHP 5.6+
     $PHPUNIT_VERSION = '4.8';
 }
 
@@ -106,7 +115,7 @@ $COMPOSER = file_exists($COMPOSER = $oldPwd.'/composer.phar')
     || ($COMPOSER = rtrim('\\' === DIRECTORY_SEPARATOR ? preg_replace('/[\r\n].*/', '', `where.exe composer.phar`) : `which composer.phar 2> /dev/null`))
     || ($COMPOSER = rtrim('\\' === DIRECTORY_SEPARATOR ? preg_replace('/[\r\n].*/', '', `where.exe composer`) : `which composer 2> /dev/null`))
     || file_exists($COMPOSER = rtrim('\\' === DIRECTORY_SEPARATOR ? `git rev-parse --show-toplevel 2> NUL` : `git rev-parse --show-toplevel 2> /dev/null`).DIRECTORY_SEPARATOR.'composer.phar')
-    ? (file_get_contents($COMPOSER, null, 0, 18) === '#!/usr/bin/env php' ? $PHP : '').' '.escapeshellarg($COMPOSER) // detect shell wrappers by looking at the shebang
+    ? (file_get_contents($COMPOSER, false, null, 0, 18) === '#!/usr/bin/env php' ? $PHP : '').' '.escapeshellarg($COMPOSER) // detect shell wrappers by looking at the shebang
     : 'composer';
 
 $SYMFONY_PHPUNIT_REMOVE = $getEnvVar('SYMFONY_PHPUNIT_REMOVE', 'phpspec/prophecy'.($PHPUNIT_VERSION < 6.0 ? ' symfony/yaml': ''));
@@ -122,25 +131,25 @@ if (!file_exists("$PHPUNIT_DIR/$PHPUNIT_VERSION_DIR/phpunit") || $configurationH
         rename("$PHPUNIT_VERSION_DIR", "$PHPUNIT_VERSION_DIR.old");
         passthru(sprintf('\\' === DIRECTORY_SEPARATOR ? 'rmdir /S /Q %s': 'rm -rf %s', "$PHPUNIT_VERSION_DIR.old"));
     }
-    passthru("$COMPOSER create-project --no-install --prefer-dist --no-scripts --no-plugins --no-progress --ansi phpunit/phpunit $PHPUNIT_VERSION_DIR \"$PHPUNIT_VERSION.*\"");
+    $passthruOrFail("$COMPOSER create-project --no-install --prefer-dist --no-scripts --no-plugins --no-progress --ansi phpunit/phpunit $PHPUNIT_VERSION_DIR \"$PHPUNIT_VERSION.*\"");
     @copy("$PHPUNIT_VERSION_DIR/phpunit.xsd", 'phpunit.xsd');
     chdir("$PHPUNIT_VERSION_DIR");
     if ($SYMFONY_PHPUNIT_REMOVE) {
-        passthru("$COMPOSER remove --no-update ".$SYMFONY_PHPUNIT_REMOVE);
+        $passthruOrFail("$COMPOSER remove --no-update ".$SYMFONY_PHPUNIT_REMOVE);
     }
     if (5.1 <= $PHPUNIT_VERSION && $PHPUNIT_VERSION < 5.4) {
-        passthru("$COMPOSER require --no-update phpunit/phpunit-mock-objects \"~3.1.0\"");
+        $passthruOrFail("$COMPOSER require --no-update phpunit/phpunit-mock-objects \"~3.1.0\"");
     }
 
-    passthru("$COMPOSER config --unset platform");
+    $passthruOrFail("$COMPOSER config --unset platform");
     if (file_exists($path = $root.'/vendor/symfony/phpunit-bridge')) {
-        passthru("$COMPOSER require --no-update symfony/phpunit-bridge \"*@dev\"");
-        passthru("$COMPOSER config repositories.phpunit-bridge path ".escapeshellarg(str_replace('/', DIRECTORY_SEPARATOR, $path)));
+        $passthruOrFail("$COMPOSER require --no-update symfony/phpunit-bridge \"*@dev\"");
+        $passthruOrFail("$COMPOSER config repositories.phpunit-bridge path ".escapeshellarg(str_replace('/', DIRECTORY_SEPARATOR, $path)));
         if ('\\' === DIRECTORY_SEPARATOR) {
             file_put_contents('composer.json', preg_replace('/^( {8})"phpunit-bridge": \{$/m', "$0\n$1    ".'"options": {"symlink": false},', file_get_contents('composer.json')));
         }
     } else {
-        passthru("$COMPOSER require --no-update symfony/phpunit-bridge \"*\"");
+        $passthruOrFail("$COMPOSER require --no-update symfony/phpunit-bridge \"*\"");
     }
     $prevRoot = getenv('COMPOSER_ROOT_VERSION');
     putenv("COMPOSER_ROOT_VERSION=$PHPUNIT_VERSION.99");
@@ -206,7 +215,7 @@ if (isset($argv[1]) && 'symfony' === $argv[1] && !file_exists('symfony') && file
     $argv[1] = 'src/Symfony';
 }
 if (isset($argv[1]) && is_dir($argv[1]) && !file_exists($argv[1].'/phpunit.xml.dist')) {
-    // Find Symfony components in plain PHP for Windows portability
+    // Find Symfony components in plain php for Windows portability
 
     $finder = new RecursiveDirectoryIterator($argv[1], FilesystemIterator::KEY_AS_FILENAME | FilesystemIterator::UNIX_PATHS);
     $finder = new RecursiveIteratorIterator($finder);
diff --git a/src/Symfony/Component/Process/Process.php b/src/Symfony/Component/Process/Process.php
index d1775b797f..3b8c4cb443 100644
--- a/src/Symfony/Component/Process/Process.php
+++ b/src/Symfony/Component/Process/Process.php
@@ -135,7 +135,7 @@ class Process implements \IteratorAggregate
      * @param mixed|null     $input   The input as stream resource, scalar or \Traversable, or null for no input
      * @param int|float|null $timeout The timeout in seconds or null to disable
      *
-     * @throws RuntimeException When proc_open is not installed
+     * @throws LogicException When proc_open is not installed
      */
     public function __construct($command, string $cwd = null, array $env = null, $input = null, ?float $timeout = 60)
     {
@@ -188,7 +188,7 @@ class Process implements \IteratorAggregate
      *
      * @return static
      *
-     * @throws RuntimeException When proc_open is not installed
+     * @throws LogicException When proc_open is not installed
      */
     public static function fromShellCommandline(string $command, string $cwd = null, array $env = null, $input = null, ?float $timeout = 60)
     {
@@ -223,9 +223,11 @@ class Process implements \IteratorAggregate
      *
      * @return int The exit status code
      *
-     * @throws RuntimeException When process can't be launched
-     * @throws RuntimeException When process stopped after receiving signal
-     * @throws LogicException   In case a callback is provided and output has been disabled
+     * @throws RuntimeException         When process can't be launched
+     * @throws RuntimeException         When process is already running
+     * @throws ProcessTimedOutException When process timed out
+     * @throws ProcessSignaledException When process stopped after receiving signal
+     * @throws LogicException           In case a callback is provided and output has been disabled
      *
      * @final
      */
@@ -393,9 +395,9 @@ class Process implements \IteratorAggregate
      *
      * @return int The exitcode of the process
      *
-     * @throws RuntimeException When process timed out
-     * @throws RuntimeException When process stopped after receiving signal
-     * @throws LogicException   When process is not yet started
+     * @throws ProcessTimedOutException When process timed out
+     * @throws ProcessSignaledException When process stopped after receiving signal
+     * @throws LogicException           When process is not yet started
      */
     public function wait(callable $callback = null)
     {
@@ -406,7 +408,7 @@ class Process implements \IteratorAggregate
         if (null !== $callback) {
             if (!$this->processPipes->haveReadSupport()) {
                 $this->stop(0);
-                throw new \LogicException('Pass the callback to the "Process::start" method or call enableOutput to use a callback with "Process::wait"');
+                throw new LogicException('Pass the callback to the "Process::start" method or call enableOutput to use a callback with "Process::wait"');
             }
             $this->callback = $this->buildCallback($callback);
         }
@@ -436,8 +438,9 @@ class Process implements \IteratorAggregate
      * from the output in real-time while writing the standard input to the process.
      * It allows to have feedback from the independent process during execution.
      *
-     * @throws RuntimeException When process timed out
-     * @throws LogicException   When process is not yet started
+     * @throws RuntimeException         When process timed out
+     * @throws LogicException           When process is not yet started
+     * @throws ProcessTimedOutException In case the timeout was reached
      */
     public function waitUntil(callable $callback): bool
     {
@@ -446,7 +449,7 @@ class Process implements \IteratorAggregate
 
         if (!$this->processPipes->haveReadSupport()) {
             $this->stop(0);
-            throw new \LogicException('Pass the callback to the "Process::start" method or call enableOutput to use a callback with "Process::waitUntil".');
+            throw new LogicException('Pass the callback to the "Process::start" method or call enableOutput to use a callback with "Process::waitUntil".');
         }
         $callback = $this->buildCallback($callback);