diff --git a/core/lib/Drupal/Core/Database/Install/Tasks.php b/core/lib/Drupal/Core/Database/Install/Tasks.php
index ee9c23e..409c859 100644
--- a/core/lib/Drupal/Core/Database/Install/Tasks.php
+++ b/core/lib/Drupal/Core/Database/Install/Tasks.php
@@ -148,14 +148,19 @@ public function runTasks() {
       }
     }
     // Check for failed results and compile message
-    $message = '';
+    $errors = [];
     foreach ($this->results as $result => $success) {
       if (!$success) {
-        $message = SafeMarkup::isSafe($result) ? $result : SafeMarkup::checkPlain($result);
+        $errors[] = $result;
       }
     }
-    if (!empty($message)) {
-      $message = SafeMarkup::set('Resolve all issues below to continue the installation. For help configuring your database server, see the <a href="https://www.drupal.org/getting-started/install">installation handbook</a>, or contact your hosting provider.' . $message);
+    if ($errors) {
+      $error_list = [
+        '#theme' => 'item_list',
+        '#items' => $errors,
+      ];
+      $error_list = \Drupal::service('renderer')->renderPlain($error_list);
+      $message = t('Resolve all issues below to continue the installation. For help configuring your database server, see the <a href="https://www.drupal.org/getting-started/install">installation handbook</a>, or contact your hosting provider.@errors', ['@errors' => $error_list]);
       throw new TaskException($message);
     }
   }
diff --git a/core/modules/system/src/Tests/Installer/InstallerNotValidDatabaseSettingsTest.php b/core/modules/system/src/Tests/Installer/InstallerNotValidDatabaseSettingsTest.php
new file mode 100644
index 0000000..a104368
--- /dev/null
+++ b/core/modules/system/src/Tests/Installer/InstallerNotValidDatabaseSettingsTest.php
@@ -0,0 +1,53 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\system\Tests\Installer\InstallerNotValidDatabaseSettingsTest.
+ */
+
+namespace Drupal\system\Tests\Installer;
+
+use Drupal\Core\Database\Database;
+use Drupal\simpletest\InstallerTestBase;
+
+/**
+ * Tests the installer with an existing settings file with database connection
+ * info.
+ *
+ * @group Installer
+ */
+class InstallerNotValidDatabaseSettingsTest extends InstallerTestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp() {
+    // Pre-configure database credentials in settings.php.
+    $connection_info = Database::getConnectionInfo();
+    unset($connection_info['default']['pdo']);
+    unset($connection_info['default']['init_commands']);
+
+    $this->settings['databases']['default'] = (object) array(
+      'value' => $connection_info,
+      'required' => TRUE,
+    );
+    parent::setUp();
+  }
+
+  /**
+   * For testing database failures.
+   */
+  protected function setupSettings() {
+    // All database settings should be pre-configured, except password.
+    $values = $this->parameters['forms']['install_settings_form'];
+    $driver = $values['driver'];
+    $edit = array();
+    $edit = $this->translatePostValues(array(
+      $driver => array(
+        'password' => $this->randomMachineName(),
+      ),
+    ));
+    $this->drupalPostForm(NULL, $edit, $this->translations['Save and continue']);
+  }
+
+}