diff --git a/core/INSTALL.txt b/core/INSTALL.txt
index 3ae63b882f..18df90ff3e 100644
--- a/core/INSTALL.txt
+++ b/core/INSTALL.txt
@@ -15,7 +15,7 @@ QUICKSTART
 ----------------------
 
 Prerequisites:
-- PHP 7.3.0 (or greater) (https://php.net).
+- PHP 7.4.0 (or greater) (https://php.net).
 
 In the instructions below, replace the version x.y.z with the specific version
 you wish to download. Example: 8.6.0.zip. You can find the latest stable version
@@ -48,8 +48,10 @@ Drupal requires:
 - A web server with PHP support, for example:
   - Apache 2.4.7 (or greater) (http://httpd.apache.org/).
   - Nginx 1.1 (or greater) (http://nginx.com/).
-- PHP 7.3.0 (or greater) (http://php.net/). For better security support it is
-  recommended to update to at least 7.3.13.
+- PHP 7.4.0 (or greater) (http://php.net/). (For backwards compatibility, it is
+  technically possible to install Drupal on PHP 7.3, but this is not supported
+  and may fail in a future release.) For better security support, update to at
+  least PHP 8.0.2.
 - One of the following databases:
   - MySQL 5.7.8 (or greater) (http://www.mysql.com/).
   - MariaDB 10.3.7 (or greater) (https://mariadb.org/). MariaDB is a fully
diff --git a/core/drupalci.yml b/core/drupalci.yml
index 413272eff3..c1a27e628f 100644
--- a/core/drupalci.yml
+++ b/core/drupalci.yml
@@ -7,43 +7,12 @@
 build:
   assessment:
     testing:
-      # Run code quality checks.
-      container_command.commit-checks:
-        commands:
-          - "core/scripts/dev/commit-code-check.sh --drupalci"
-        halt-on-fail: true
       # run_tests task is executed several times in order of performance speeds.
       # halt-on-fail can be set on the run_tests tasks in order to fail fast.
       # suppress-deprecations is false in order to be alerted to usages of
       # deprecated code.
       run_tests.phpunit:
         types: 'PHPUnit-Unit'
-        testgroups: '--all'
+        testgroups: '--group Command'
         suppress-deprecations: false
         halt-on-fail: false
-      run_tests.kernel:
-        types: 'PHPUnit-Kernel'
-        testgroups: '--all'
-        suppress-deprecations: false
-        halt-on-fail: false
-      run_tests.build:
-        # Limit concurrency due to disk space concerns.
-        concurrency: 15
-        types: 'PHPUnit-Build'
-        testgroups: '--all'
-        suppress-deprecations: false
-        halt-on-fail: false
-      run_tests.functional:
-        types: 'PHPUnit-Functional'
-        testgroups: '--all'
-        suppress-deprecations: false
-        halt-on-fail: false
-      run_tests.javascript:
-        concurrency: 15
-        types: 'PHPUnit-FunctionalJavascript'
-        testgroups: '--all'
-        suppress-deprecations: false
-        halt-on-fail: false
-      # Run nightwatch testing.
-      # @see https://www.drupal.org/project/drupal/issues/2869825
-      nightwatchjs: {}
diff --git a/core/install.php b/core/install.php
index 422cc099c5..52cf865c4f 100644
--- a/core/install.php
+++ b/core/install.php
@@ -30,7 +30,7 @@
 // in the printed message to the user) whenever \Drupal::MINIMUM_PHP is
 // updated.
 if (version_compare(PHP_VERSION, '7.3.0') < 0) {
-  print 'Your PHP installation is too old. Drupal requires at least PHP 7.3.0. See the <a href="https://www.drupal.org/docs/9/how-drupal-9-is-made-and-what-is-included/environment-requirements-of-drupal-9#s-php-version-requirement">Environment requirements of Drupal 9</a> page for more information.';
+  print 'Your PHP installation is too old. Drupal installation requires at least PHP 7.3.0, and only PHP 7.4.0 and higher are fully supported. See the <a href="https://www.drupal.org/docs/9/how-drupal-9-is-made-and-what-is-included/environment-requirements-of-drupal-9#s-php-version-requirement">Environment requirements of Drupal 9</a> page for more information.';
   exit;
 }
 
diff --git a/core/lib/Drupal.php b/core/lib/Drupal.php
index 6ab16c58dc..5317d46bd9 100644
--- a/core/lib/Drupal.php
+++ b/core/lib/Drupal.php
@@ -96,7 +96,7 @@ class Drupal {
    *   that Drupal no longer supports that PHP version.
    * - An error is shown in the status report that the PHP version is too old.
    */
-  const MINIMUM_SUPPORTED_PHP = '7.3.0';
+  const MINIMUM_SUPPORTED_PHP = '7.4.0';
 
   /**
    * Minimum allowed version of PHP for Drupal to be bootstrapped.
diff --git a/core/modules/system/system.install b/core/modules/system/system.install
index 2e1bab4caa..6c1ff864a6 100644
--- a/core/modules/system/system.install
+++ b/core/modules/system/system.install
@@ -294,7 +294,7 @@ function system_requirements($phase) {
         ':php_requirements' => 'https://www.drupal.org/docs/9/how-drupal-9-is-made-and-what-is-included/environment-requirements-of-drupal-9#s-php-version-requirement',
       ]
     );
-    $requirements['php']['severity'] = REQUIREMENT_ERROR;
+    $requirements['php']['severity'] = REQUIREMENT_WARNING;
 
     // If the PHP version is also below the absolute minimum allowed, it's not
     // safe to continue with the requirements check.
diff --git a/core/tests/Drupal/Tests/Core/Command/QuickStartTest.php b/core/tests/Drupal/Tests/Core/Command/QuickStartTest.php
index 9da1c86b54..1fbd7840cc 100644
--- a/core/tests/Drupal/Tests/Core/Command/QuickStartTest.php
+++ b/core/tests/Drupal/Tests/Core/Command/QuickStartTest.php
@@ -165,7 +165,7 @@ public function testPhpRequirement() {
 
     $error_output = $process->getErrorOutput();
     $this->assertStringContainsString('Your PHP installation is too old.', $error_output);
-    $this->assertStringContainsString('Drupal requires at least PHP', $error_output);
+    $this->assertStringContainsString('Drupal installation requires at least PHP', $error_output);
     $this->assertStringContainsString(\Drupal::MINIMUM_SUPPORTED_PHP, $error_output);
 
     // Stop the web server.