diff -u b/core/modules/system/system.install b/core/modules/system/system.install
--- b/core/modules/system/system.install
+++ b/core/modules/system/system.install
@@ -5,7 +5,6 @@
  * Install, update and uninstall functions for the system module.
  */
 
-use Drupal\block\Entity\Block;
 use Drupal\Component\Utility\Crypt;
 use Drupal\Component\Utility\Environment;
 use Drupal\Component\Utility\SafeMarkup;
@@ -1132,6 +1131,7 @@
   /** @var \Drupal\Core\Extension\Extension $theme */
   foreach ($theme_handler->listInfo() as $theme) {
     $theme_name = $theme->getName();
+    $block_storage = \Drupal::entityManager()->getStorage('block');
     switch ($theme_name) {
       case 'bartik':
         if (!$config_storage->exists('block.block.bartik_local_actions')) {
@@ -1140,7 +1140,7 @@
             'theme' => 'bartik',
             'weight' => -20,
           ] + $local_actions_default_settings;
-          \Drupal::entityManager()->getStorage('block')->create($values)->save();
+          $block_storage->create($values)->save();
         }
         if (!$config_storage->exists('block.block.bartik_tabs')) {
           $values = [
@@ -1148,7 +1148,7 @@
             'theme' => 'bartik',
             'weight' => -30,
           ] + $tabs_default_settings;
-          \Drupal::entityManager()->getStorage('block')->create($values)->save();
+          $block_storage->create($values)->save();
         }
         break;
 
@@ -1159,7 +1159,7 @@
             'theme' => 'seven',
             'weight' => -10,
           ] + $local_actions_default_settings;
-          \Drupal::entityManager()->getStorage('block')->create($values)->save();
+          $block_storage->create($values)->save();
         }
         if (!$config_storage->exists('block.block.seven_primary_tabs')) {
           $values = [
@@ -1172,7 +1172,7 @@
               'secondary' => FALSE,
             ],
           ] + $tabs_default_settings;
-          \Drupal::entityManager()->getStorage('block')->create($values)->save();
+          $block_storage->create($values)->save();
         }
 
         if (!$config_storage->exists('block.block.seven_secondary_tabs')) {
@@ -1186,7 +1186,7 @@
               'secondary' => TRUE,
             ],
           ] + $tabs_default_settings;
-          \Drupal::entityManager()->getStorage('block')->create($values)->save();
+          $block_storage->create($values)->save();
         }
         break;
 
@@ -1196,14 +1196,14 @@
             'id' => 'stark_local_actions',
             'theme' => 'stark',
           ] + $local_actions_default_settings;
-          \Drupal::entityManager()->getStorage('block')->create($values)->save();
+          $block_storage->create($values)->save();
         }
         if (!$config_storage->exists('block.block.stark_tabs')) {
           $values = [
             'id' => 'stark_tabs',
             'theme' => 'stark',
           ] + $tabs_default_settings;
-          \Drupal::entityManager()->getStorage('block')->create($values)->save();
+          $block_storage->create($values)->save();
         }
         break;
 
@@ -1219,7 +1219,7 @@
             'theme' => $theme_name,
             'weight' => -10,
           ] + $local_actions_default_settings;
-          \Drupal::entityManager()->getStorage('block')->create($values)->save();
+          $block_storage->create($values)->save();
         }
         if (!$config_storage->exists(sprintf('block.block.%s_tabs', $theme_name))) {
           $values = [
@@ -1227,7 +1227,7 @@
             'theme' => $theme_name,
             'weight' => -20,
           ] + $tabs_default_settings;
-          \Drupal::entityManager()->getStorage('block')->create($values)->save();
+          $block_storage->create($values)->save();
         }
         break;
     }