diff --git a/core/lib/Drupal/Core/DrupalKernel.php b/core/lib/Drupal/Core/DrupalKernel.php
index 23524650c2..30ea156e42 100644
--- a/core/lib/Drupal/Core/DrupalKernel.php
+++ b/core/lib/Drupal/Core/DrupalKernel.php
@@ -618,17 +618,18 @@ public function discoverServiceProviders() {
     // Retrieve enabled modules and register their namespaces.
     if (!isset($this->moduleList)) {
       $extensions = $this->getConfigStorage()->read('core.extension');
-      // If core.extension configuration does not exist then the container
-      // cannot be dumped because Drupal is yet to be installed.
-      if ($extensions === FALSE && $this->environment !== 'testing' && !InstallerKernel::installationAttempted()) {
+      // If core.extension configuration does not exist and we're not in the
+      // installer itself, then we need to put the kernel into a pre-installer
+      // mode. The container should not be dumped because Drupal is yet to be
+      // installed. The installer service provider is registered to ensure that
+      // cache and other automatically created tables are not created if
+      // database settings are available. None of this is required when the
+      // installer is running because the installer has its own kernel and
+      // manages the addition of its own service providers.
+      // @see \Drupal\KernelTests\KernelTestBase::bootKernel()
+      if ($extensions === FALSE && !InstallerKernel::installationAttempted()) {
         $this->allowDumping = FALSE;
         $this->containerNeedsDumping = FALSE;
-        // If we're not in the installer, register the installer service
-        // provider to ensure that cache tables are not created. This is
-        // required to correctly redirect to the installer without creating any
-        // incorrect caches. This is not required when the installer is running
-        // because the installer manages the addition of its own service
-        // providers.
         $GLOBALS['conf']['container_service_providers']['InstallerServiceProvider'] = 'Drupal\Core\Installer\InstallerServiceProvider';
       }
       $this->moduleList = isset($extensions['module']) ? $extensions['module'] : [];
diff --git a/core/tests/Drupal/KernelTests/KernelTestBase.php b/core/tests/Drupal/KernelTests/KernelTestBase.php
index 4539ed4850..032a5d62b8 100644
--- a/core/tests/Drupal/KernelTests/KernelTestBase.php
+++ b/core/tests/Drupal/KernelTests/KernelTestBase.php
@@ -341,10 +341,11 @@ private function bootKernel() {
     $kernel = new DrupalKernel('testing', $this->classLoader, FALSE);
     $kernel->setSitePath($this->siteDirectory);
     // Boot a new one-time container from scratch. Ensure to set the module list
-    // upfront to avoid a subsequent rebuild.
-    if ($modules && $extensions = $this->getExtensionsForModules($modules)) {
-      $kernel->updateModules($extensions, $extensions);
-    }
+    // upfront to avoid a subsequent rebuild or setting the kernel into the
+    // pre-installer mode.
+    $extensions = $modules ? $this->getExtensionsForModules($modules) : [];
+    $kernel->updateModules($extensions, $extensions);
+
     // DrupalKernel::boot() is not sufficient as it does not invoke preHandle(),
     // which is required to initialize legacy global variables.
     $request = Request::create('/');