diff --git a/core/modules/system/src/Controller/SystemInfoController.php b/core/modules/system/src/Controller/SystemInfoController.php
index cdf0195583..1cb14f0b2c 100644
--- a/core/modules/system/src/Controller/SystemInfoController.php
+++ b/core/modules/system/src/Controller/SystemInfoController.php
@@ -2,6 +2,7 @@
 
 namespace Drupal\system\Controller;
 
+use Drupal\Core\StringTranslation\StringTranslationTrait;
 use Symfony\Component\DependencyInjection\ContainerInterface;
 use Symfony\Component\HttpFoundation\Response;
 use Drupal\Core\DependencyInjection\ContainerInjectionInterface;
@@ -12,6 +13,8 @@
  */
 class SystemInfoController implements ContainerInjectionInterface {
 
+  use StringTranslationTrait;
+
   /**
    * System Manager Service.
    *
diff --git a/core/modules/system/src/Element/StatusReportPage.php b/core/modules/system/src/Element/StatusReportPage.php
index 6c7f783fd0..e779b255d2 100644
--- a/core/modules/system/src/Element/StatusReportPage.php
+++ b/core/modules/system/src/Element/StatusReportPage.php
@@ -5,6 +5,7 @@
 use Drupal\Core\Render\Element\RenderElement;
 use Drupal\Core\Render\Element\StatusReport;
 use Drupal\Core\StringTranslation\PluralTranslatableMarkup;
+use Drupal\Core\StringTranslation\TranslatableMarkup;
 
 /**
  * Creates status report page element.
@@ -76,18 +77,18 @@ public static function preRenderCounters($element) {
     $counters = [
       'error' => [
         'amount' => 0,
-        'text' => t('Error'),
-        'text_plural' => t('Errors'),
+        'text' => new TranslatableMarkup('Error'),
+        'text_plural' => new TranslatableMarkup('Errors'),
       ],
       'warning' => [
         'amount' => 0,
-        'text' => t('Warning'),
-        'text_plural' => t('Warnings'),
+        'text' => new TranslatableMarkup('Warning'),
+        'text_plural' => new TranslatableMarkup('Warnings'),
       ],
       'checked' => [
         'amount' => 0,
-        'text' => t('Checked', [], ['context' => 'Examined']),
-        'text_plural' => t('Checked', [], ['context' => 'Examined']),
+        'text' => new TranslatableMarkup('Checked', [], ['context' => 'Examined']),
+        'text_plural' => new TranslatableMarkup('Checked', [], ['context' => 'Examined']),
       ],
     ];
 
diff --git a/core/modules/system/src/Form/PrepareModulesEntityUninstallForm.php b/core/modules/system/src/Form/PrepareModulesEntityUninstallForm.php
index a65716b718..65097463c9 100644
--- a/core/modules/system/src/Form/PrepareModulesEntityUninstallForm.php
+++ b/core/modules/system/src/Form/PrepareModulesEntityUninstallForm.php
@@ -5,6 +5,7 @@
 use Drupal\Core\Entity\EntityTypeManagerInterface;
 use Drupal\Core\Form\ConfirmFormBase;
 use Drupal\Core\Form\FormStateInterface;
+use Drupal\Core\StringTranslation\TranslatableMarkup;
 use Drupal\Core\Url;
 use Symfony\Component\DependencyInjection\ContainerInterface;
 use Symfony\Component\HttpFoundation\RedirectResponse;
@@ -234,8 +235,11 @@ public static function deleteContentEntities($entity_type_id, &$context) {
     // estimation of the completion level we reached.
     if (count($entity_ids) > 0 && $context['sandbox']['progress'] != $context['sandbox']['max']) {
       $context['finished'] = $context['sandbox']['progress'] / $context['sandbox']['max'];
-      $context['message'] = t('Deleting items... Completed @percentage% (@current of @total).', ['@percentage' => round(100 * $context['sandbox']['progress'] / $context['sandbox']['max']), '@current' => $context['sandbox']['progress'], '@total' => $context['sandbox']['max']]);
-
+      $context['message'] = new TranslatableMarkup('Deleting items... Completed @percentage% (@current of @total).', [
+        '@percentage' => round(100 * $context['sandbox']['progress'] / $context['sandbox']['max']),
+        '@current' => $context['sandbox']['progress'],
+        '@total' => $context['sandbox']['max'],
+      ]);
     }
     else {
       $context['finished'] = 1;
@@ -250,7 +254,7 @@ public static function deleteContentEntities($entity_type_id, &$context) {
    */
   public static function moduleBatchFinished($success, $results, $operations) {
     $entity_type_plural = \Drupal::entityTypeManager()->getDefinition($results['entity_type_id'])->getPluralLabel();
-    \Drupal::messenger()->addStatus(t('All @entity_type_plural have been deleted.', ['@entity_type_plural' => $entity_type_plural]));
+    \Drupal::messenger()->addStatus(new TranslatableMarkup('All @entity_type_plural have been deleted.', ['@entity_type_plural' => $entity_type_plural]));
 
     return new RedirectResponse(Url::fromRoute('system.modules_uninstall')->setAbsolute()->toString());
   }
diff --git a/core/modules/system/src/Form/RegionalForm.php b/core/modules/system/src/Form/RegionalForm.php
index ebbbab6e43..16a24147d4 100644
--- a/core/modules/system/src/Form/RegionalForm.php
+++ b/core/modules/system/src/Form/RegionalForm.php
@@ -88,7 +88,15 @@ public function buildForm(array $form, FormStateInterface $form_state) {
       '#type' => 'select',
       '#title' => $this->t('First day of week'),
       '#default_value' => $system_date->get('first_day'),
-      '#options' => [0 => $this->t('Sunday'), 1 => $this->t('Monday'), 2 => $this->t('Tuesday'), 3 => $this->t('Wednesday'), 4 => $this->t('Thursday'), 5 => $this->t('Friday'), 6 => $this->t('Saturday')],
+      '#options' => [
+        0 => $this->t('Sunday'),
+        1 => $this->t('Monday'),
+        2 => $this->t('Tuesday'),
+        3 => $this->t('Wednesday'),
+        4 => $this->t('Thursday'),
+        5 => $this->t('Friday'),
+        6 => $this->t('Saturday'),
+      ],
     ];
 
     $form['timezone'] = [
diff --git a/core/modules/system/src/Form/SiteMaintenanceModeForm.php b/core/modules/system/src/Form/SiteMaintenanceModeForm.php
index 54dc4fb64f..eaf56a5c61 100644
--- a/core/modules/system/src/Form/SiteMaintenanceModeForm.php
+++ b/core/modules/system/src/Form/SiteMaintenanceModeForm.php
@@ -83,7 +83,11 @@ public function buildForm(array $form, FormStateInterface $form_state) {
       '#type' => 'checkbox',
       '#title' => $this->t('Put site into maintenance mode'),
       '#default_value' => $this->state->get('system.maintenance_mode'),
-      '#description' => $this->t('Visitors will only see the maintenance mode message. Only users with the "@permission-label" <a href=":permissions-url">permission</a> will be able to access the site. Authorized users can log in directly via the <a href=":user-login">user login</a> page.', ['@permission-label' => $permission_label, ':permissions-url' => Url::fromRoute('user.admin_permissions')->toString(), ':user-login' => Url::fromRoute('user.login')->toString()]),
+      '#description' => $this->t('Visitors will only see the maintenance mode message. Only users with the "@permission-label" <a href=":permissions-url">permission</a> will be able to access the site. Authorized users can log in directly via the <a href=":user-login">user login</a> page.', [
+        '@permission-label' => $permission_label,
+        ':permissions-url' => Url::fromRoute('user.admin_permissions')->toString(),
+        ':user-login' => Url::fromRoute('user.login')->toString(),
+      ]),
     ];
     $form['maintenance_mode_message'] = [
       '#type' => 'textarea',
diff --git a/core/modules/system/src/Form/SystemBrandingOffCanvasForm.php b/core/modules/system/src/Form/SystemBrandingOffCanvasForm.php
index d0dea9b111..6cf135c272 100644
--- a/core/modules/system/src/Form/SystemBrandingOffCanvasForm.php
+++ b/core/modules/system/src/Form/SystemBrandingOffCanvasForm.php
@@ -8,6 +8,7 @@
 use Drupal\Core\Form\FormStateInterface;
 use Drupal\Core\Plugin\PluginFormBase;
 use Drupal\Core\Session\AccountInterface;
+use Drupal\Core\StringTranslation\StringTranslationTrait;
 use Symfony\Component\DependencyInjection\ContainerInterface;
 
 /**
@@ -17,6 +18,8 @@
  */
 class SystemBrandingOffCanvasForm extends PluginFormBase implements ContainerInjectionInterface {
 
+  use StringTranslationTrait;
+
   /**
    * The block plugin.
    *