diff -u b/core/lib/Drupal/Core/Entity/Sql/SqlContentEntityStorage.php b/core/lib/Drupal/Core/Entity/Sql/SqlContentEntityStorage.php
--- b/core/lib/Drupal/Core/Entity/Sql/SqlContentEntityStorage.php
+++ b/core/lib/Drupal/Core/Entity/Sql/SqlContentEntityStorage.php
@@ -1509,7 +1509,7 @@
     }
 
     // Update the field schema.
-    $this->schemaHandler()->prepareFieldSchemaDeletion($storage_definition);
+    $this->schemaHandler()->onFieldStorageDefinitionDelete($storage_definition);
   }
 
   /**
reverted:
--- b/core/modules/system/system.module
+++ a/core/modules/system/system.module
@@ -5,21 +5,20 @@
  * Configuration system that lets administrators modify the workings of the site.
  */
 
-use Drupal\Component\Plugin\Exception\PluginNotFoundException;
-use Drupal\Core\Block\BlockPluginInterface;
 use Drupal\Core\Cache\Cache;
-use Drupal\Core\Entity\ContentEntityTypeInterface;
 use Drupal\Core\Extension\Extension;
 use Drupal\Core\Extension\ExtensionDiscovery;
+use Drupal\Core\Form\FormState;
 use Drupal\Core\Form\FormStateInterface;
+use Drupal\Core\Routing\RouteMatchInterface;
+use Drupal\Core\StringTranslation\TranslationWrapper;
 use Drupal\Core\Language\LanguageInterface;
 use Drupal\Core\Menu\MenuTreeParameters;
-use Drupal\Core\Routing\RouteMatchInterface;
-use Drupal\Core\StringTranslation\TranslationWrapper;
 use Drupal\Core\Url;
+use Drupal\Core\Block\BlockPluginInterface;
 use Drupal\user\UserInterface;
+use Symfony\Component\HttpFoundation\RedirectResponse;
 use GuzzleHttp\Exception\RequestException;
-use Symfony\Component\HttpFoundation\RedirectResponse;
 
 /**
  * New users will be set to the default time zone at registration.
@@ -1033,42 +1032,11 @@
  * Implements hook_system_info_alter().
  */
 function system_system_info_alter(&$info, Extension $file, $type) {
+  // Remove page-top and page-bottom from the blocks UI since they are reserved for
+  // modules to populate from outside the blocks system.
+  if ($type == 'theme') {
+    $info['regions_hidden'][] = 'page_top';
+    $info['regions_hidden'][] = 'page_bottom';
-  switch ($type) {
-    case 'theme':
-      // Remove page-top and page-bottom from the blocks UI since they are
-      // reserved for modules to populate from outside the blocks system.
-      $info['regions_hidden'][] = 'page_top';
-      $info['regions_hidden'][] = 'page_bottom';
-      break;
-
-    case 'module':
-      // @todo Unify this with field_system_info_alter() once purging is
-      //   supported for any field. See https://www.drupal.org/node/2282119.
-      $module_name = $file->getName();
-      if ($module_name != 'field') {
-        $entity_manager = \Drupal::entityManager();
-        foreach ($entity_manager->getDefinitions() as $entity_type_id => $entity_type) {
-          try {
-            // We skip entity-defining modules, otherwise deleting all entities
-            // would be required before being able to uninstall them.
-            if ($entity_type instanceof ContentEntityTypeInterface && $entity_type->getProvider() != $module_name && $entity_manager->getStorage($entity_type_id)->hasData()) {
-              foreach ($entity_manager->getFieldStorageDefinitions($entity_type_id) as $definition) {
-                if ($definition->getProvider() == $module_name) {
-                  $info['required'] = TRUE;
-                  $info['explanation'] = t('Fields type(s) in use');
-                  break;
-                }
-              }
-            }
-          }
-          catch (PluginNotFoundException $e) {
-            // This may happen if the current module is being installed. In this
-            // case we can safely ignore it, as we are interested in blocking
-            // module uninstallation.
-          }
-        }
-      }
-      break;
   }
 }