diff --git a/.htaccess b/.htaccess
index 83cb71a042..7d63a98c64 100644
--- a/.htaccess
+++ b/.htaccess
@@ -29,7 +29,6 @@ AddEncoding gzip svgz
 
 # PHP 5, Apache 1 and 2.
 <IfModule mod_php5.c>
-  php_value assert.active                   0
   php_flag session.auto_start               off
   php_value mbstring.http_input             pass
   php_value mbstring.http_output            pass
diff --git a/core/lib/Drupal/Component/Assertion/Handle.php b/core/lib/Drupal/Component/Assertion/Handle.php
index f1e1e6ace0..5020333f8b 100644
--- a/core/lib/Drupal/Component/Assertion/Handle.php
+++ b/core/lib/Drupal/Component/Assertion/Handle.php
@@ -5,10 +5,21 @@
 /**
  * Handler for runtime assertion failures.
  *
- * This class allows PHP 5.x to throw exceptions on runtime assertion fails
+ * This class allowed PHP 5.x to throw exceptions on runtime assertion fails
  * in the same manner as PHP 7, and sets the ASSERT_EXCEPTION flag to TRUE
  * for the PHP 7 runtime.
  *
+ * The PHP group has recommended that the assert_option() function be avoided
+ * entirely, so the function of this class becomes deprecated and it now simply
+ * returns doing nothing. Assertions should be controlled from the environment,
+ * not from the Drupal codebase.
+ *
+ * This class is called from the default settings.local.php file, a file highly
+ * likely to have been modified in local environments, so instead of removing it
+ * immediately it now returns doing nothing. This class will be removed when
+ * PHP 5 support is dropped entirely, currently scheduled for 8.6.
+ *
+ * @deprecated
  * @ingroup php_assert
  */
 class Handle {
@@ -17,25 +28,7 @@ class Handle {
    * Registers uniform assertion handling.
    */
   public static function register() {
-    // Since we're using exceptions, turn error warnings off.
-    assert_options(ASSERT_WARNING, FALSE);
-
-    if (version_compare(PHP_VERSION, '7.0.0-dev') < 0) {
-      if (!class_exists('AssertionError', FALSE)) {
-        require __DIR__ . '/global_namespace_php5.php';
-      }
-      // PHP 5 - create a handler to throw the exception directly.
-      assert_options(ASSERT_CALLBACK, function ($file = '', $line = 0, $code = '', $message = '') {
-        if (empty($message)) {
-          $message = $code;
-        }
-        throw new \AssertionError($message, 0, NULL, $file, $line);
-      });
-    }
-    else {
-      // PHP 7 - just turn exception throwing on.
-      assert_options(ASSERT_EXCEPTION, TRUE);
-    }
+    return;
   }
 
 }
diff --git a/core/lib/Drupal/Component/Assertion/global_namespace_php5.php b/core/lib/Drupal/Component/Assertion/global_namespace_php5.php
deleted file mode 100644
index 1b5caf46ea..0000000000
--- a/core/lib/Drupal/Component/Assertion/global_namespace_php5.php
+++ /dev/null
@@ -1,28 +0,0 @@
-<?php
-
-/**
- * @file
- * Contains PHP5 version of the \AssertionError class.
- */
-
-/**
- * Emulates PHP 7 AssertionError as closely as possible.
- *
- * This class is declared in the global namespace. It will only be included by
- * \Drupal\Component\Assertion\Handle for PHP5 since this class exists natively
- * in PHP 7. Note that in PHP 7 it extends from Error, not Exception, but that
- * isn't possible for PHP 5 - all exceptions must extend from exception.
- */
-class AssertionError extends Exception {
-
-  /**
-   * {@inheritdoc}
-   */
-  public function __construct($message = '', $code = 0, Exception $previous = NULL, $file = '', $line = 0) {
-    parent::__construct($message, $code, $previous);
-    // Preserve the filename and line number of the assertion failure.
-    $this->file = $file;
-    $this->line = $line;
-  }
-
-}
diff --git a/core/lib/Drupal/Core/DrupalKernel.php b/core/lib/Drupal/Core/DrupalKernel.php
index 37ed0e97a6..4ffc69b25a 100644
--- a/core/lib/Drupal/Core/DrupalKernel.php
+++ b/core/lib/Drupal/Core/DrupalKernel.php
@@ -1002,12 +1002,6 @@ public static function bootEnvironment($app_root = NULL) {
         // Simpletest's internal browser.
         define('DRUPAL_TEST_IN_CHILD_SITE', TRUE);
 
-        // Web tests are to be conducted with runtime assertions active.
-        assert_options(ASSERT_ACTIVE, TRUE);
-        // Now synchronize PHP 5 and 7's handling of assertions as much as
-        // possible.
-        Handle::register();
-
         // Log fatal errors to the test site directory.
         ini_set('log_errors', 1);
         ini_set('error_log', $app_root . '/' . $test_db->getTestSitePath() . '/error.log');
diff --git a/core/modules/simpletest/src/TestBase.php b/core/modules/simpletest/src/TestBase.php
index 260d1a34af..dfaac2c743 100644
--- a/core/modules/simpletest/src/TestBase.php
+++ b/core/modules/simpletest/src/TestBase.php
@@ -2,7 +2,6 @@
 
 namespace Drupal\simpletest;
 
-use Drupal\Component\Assertion\Handle;
 use Drupal\Component\Render\MarkupInterface;
 use Drupal\Component\Utility\Crypt;
 use Drupal\Component\Utility\SafeMarkup;
@@ -904,10 +903,6 @@ public function run(array $methods = []) {
       $this->httpAuthCredentials = $username . ':' . $password;
     }
 
-    // Force assertion failures to be thrown as AssertionError for PHP 5 & 7
-    // compatibility.
-    Handle::register();
-
     set_error_handler([$this, 'errorHandler']);
     // Iterate through all the methods in this class, unless a specific list of
     // methods to run was passed.
diff --git a/core/modules/simpletest/src/Tests/SimpleTestTest.php b/core/modules/simpletest/src/Tests/SimpleTestTest.php
index 42759c255a..28965094ca 100644
--- a/core/modules/simpletest/src/Tests/SimpleTestTest.php
+++ b/core/modules/simpletest/src/Tests/SimpleTestTest.php
@@ -161,36 +161,16 @@ public function stubTest() {
     $site_path = $this->container->get('site.path');
     file_put_contents($key_file, $private_key);
 
-    // Check to see if runtime assertions are indeed on, if successful this
-    // will be the first of sixteen passes asserted in confirmStubResults()
-    try {
-      // Test with minimum possible arguments to make sure no notice for
-      // missing argument is thrown.
-      assert(FALSE);
-      $this->fail('Runtime assertions are not working.');
-    }
-    catch (\AssertionError $e) {
-      try {
-        // Now test with an error message to ensure it is correctly passed
-        // along by the rethrow.
-        assert(FALSE, 'Lorem Ipsum');
-      }
-      catch (\AssertionError $e) {
-        $this->assertEqual($e->getMessage(), 'Lorem Ipsum', 'Runtime assertions Enabled and running.');
-      }
-    }
-    // This causes the second of the sixteen passes asserted in
+    // This causes the first of the fifteen passes asserted in
     // confirmStubResults().
     $this->pass($this->passMessage);
 
     // The first three fails are caused by enabling a non-existent module in
-    // setUp().
-
-    // This causes the fourth of the five fails asserted in
+    // setUp(). This causes the fourth of the five fails asserted in
     // confirmStubResults().
     $this->fail($this->failMessage);
 
-    // This causes the third to fifth of the sixteen passes asserted in
+    // This causes the second to fourth of the fifteen passes asserted in
     // confirmStubResults().
     $user = $this->drupalCreateUser([$this->validPermission], 'SimpleTestTest');
 
@@ -198,15 +178,15 @@ public function stubTest() {
     $this->drupalCreateUser([$this->invalidPermission]);
 
     // Test logging in as a user.
-    // This causes the sixth to tenth of the sixteen passes asserted in
+    // This causes the fifth to ninth of the fifteen passes asserted in
     // confirmStubResults().
     $this->drupalLogin($user);
 
-    // This causes the eleventh of the sixteen passes asserted in
+    // This causes the tenth of the fifteen passes asserted in
     // confirmStubResults().
     $this->pass(t('Test ID is @id.', ['@id' => $this->testId]));
 
-    // These cause the twelfth to fifteenth of the sixteen passes asserted in
+    // These cause the eleventh to fourteenth of the fifteen passes asserted in
     // confirmStubResults().
     $this->assertTrue(file_exists($site_path . '/settings.testing.php'));
     // Check the settings.testing.php file got included.
@@ -221,7 +201,7 @@ public function stubTest() {
     // Generates a warning inside a PHP function.
     array_key_exists(NULL, NULL);
 
-    // This causes the sixteenth of the sixteen passes asserted in
+    // This causes the fifteenth of the fifteen passes asserted in
     // confirmStubResults().
     $this->assertNothing();
 
@@ -265,7 +245,7 @@ public function confirmStubTestResults() {
 
     $this->assertAssertion("Debug: 'Foo'", 'Debug', 'Fail', 'SimpleTestTest.php', 'Drupal\simpletest\Tests\SimpleTestTest->stubTest()');
 
-    $this->assertEqual('16 passes, 3 fails, 2 exceptions, 3 debug messages', $this->childTestResults['summary']);
+    $this->assertEqual('15 passes, 3 fails, 2 exceptions, 3 debug messages', $this->childTestResults['summary']);
 
     $this->testIds[] = $test_id = $this->getTestIdFromResults();
     $this->assertTrue($test_id, 'Found test ID in results.');
diff --git a/core/tests/bootstrap.php b/core/tests/bootstrap.php
index 7eb6ecb70c..b74be7ea7f 100644
--- a/core/tests/bootstrap.php
+++ b/core/tests/bootstrap.php
@@ -7,7 +7,6 @@
  * @see phpunit.xml.dist
  */
 
-use Drupal\Component\Assertion\Handle;
 use Drupal\Core\Composer\Composer;
 use PHPUnit\Runner\Version;
 
@@ -176,12 +175,6 @@ function drupal_phpunit_populate_class_loader() {
 // reduce the fragility of the testing system in general.
 date_default_timezone_set('Australia/Sydney');
 
-// Runtime assertions. PHPUnit follows the php.ini assert.active setting for
-// runtime assertions. By default this setting is on. Here we make a call to
-// make PHP 5 and 7 handle assertion failures the same way, but this call does
-// not turn runtime assertions on if they weren't on already.
-Handle::register();
-
 // PHPUnit 4 to PHPUnit 6 bridge. Tests written for PHPUnit 4 need to work on
 // PHPUnit 6 with a minimum of fuss.
 if (version_compare($phpunit_version, '6.1', '>=')) {
diff --git a/sites/example.settings.local.php b/sites/example.settings.local.php
index 4a40a1318b..775bd7ad1f 100644
--- a/sites/example.settings.local.php
+++ b/sites/example.settings.local.php
@@ -14,26 +14,13 @@
  * If you are using a site name in the path, such as 'sites/example.com', copy
  * this file to 'sites/example.com/settings.local.php', and uncomment the lines
  * at the bottom of 'sites/example.com/settings.php'.
- */
-
-/**
- * Assertions.
  *
- * The Drupal project primarily uses runtime assertions to enforce the
- * expectations of the API by failing when incorrect calls are made by code
- * under development.
+ * You are strongly encouraged to enable assertions in your development
+ * environment.
  *
  * @see http://php.net/assert
  * @see https://www.drupal.org/node/2492225
- *
- * If you are using PHP 7.0 it is strongly recommended that you set
- * zend.assertions=1 in the PHP.ini file (It cannot be changed from .htaccess
- * or runtime) on development machines and to 0 in production.
- *
- * @see https://wiki.php.net/rfc/expectations
  */
-assert_options(ASSERT_ACTIVE, TRUE);
-\Drupal\Component\Assertion\Handle::register();
 
 /**
  * Enable local development services.
