diff --git a/core/lib/Drupal/Core/Entity/ContentEntityBase.php b/core/lib/Drupal/Core/Entity/ContentEntityBase.php
index 2915609..5df66a0 100644
--- a/core/lib/Drupal/Core/Entity/ContentEntityBase.php
+++ b/core/lib/Drupal/Core/Entity/ContentEntityBase.php
@@ -1198,22 +1198,26 @@ public static function baseFieldDefinitions(EntityTypeInterface $entity_type) {
       $fields[$entity_type->getKey('id')] = BaseFieldDefinition::create('integer')
         ->setLabel(new TranslatableMarkup('ID'))
         ->setReadOnly(TRUE)
+        ->setStorageRequired(TRUE)
         ->setSetting('unsigned', TRUE);
     }
     if ($entity_type->hasKey('uuid')) {
       $fields[$entity_type->getKey('uuid')] = BaseFieldDefinition::create('uuid')
         ->setLabel(new TranslatableMarkup('UUID'))
-        ->setReadOnly(TRUE);
+        ->setReadOnly(TRUE)
+        ->setStorageRequired(TRUE);
     }
     if ($entity_type->hasKey('revision')) {
       $fields[$entity_type->getKey('revision')] = BaseFieldDefinition::create('integer')
         ->setLabel(new TranslatableMarkup('Revision ID'))
         ->setReadOnly(TRUE)
+        ->setStorageRequired(TRUE)
         ->setSetting('unsigned', TRUE);
     }
     if ($entity_type->hasKey('langcode')) {
       $fields[$entity_type->getKey('langcode')] = BaseFieldDefinition::create('language')
         ->setLabel(new TranslatableMarkup('Language'))
+        ->setStorageRequired(TRUE)
         ->setDisplayOptions('view', [
           'region' => 'hidden',
         ])
diff --git a/core/lib/Drupal/Core/Entity/EntityFieldManager.php b/core/lib/Drupal/Core/Entity/EntityFieldManager.php
index 378a95c..c8293fa 100644
--- a/core/lib/Drupal/Core/Entity/EntityFieldManager.php
+++ b/core/lib/Drupal/Core/Entity/EntityFieldManager.php
@@ -216,7 +216,8 @@ protected function buildBaseFieldDefinitions($entity_type_id) {
           ->setDescription($this->t('A flag indicating whether this is the default translation.'))
           ->setTranslatable(TRUE)
           ->setRevisionable(TRUE)
-          ->setDefaultValue(TRUE);
+          ->setDefaultValue(TRUE)
+          ->setRequired(TRUE);
       }
     }
 
diff --git a/core/lib/Drupal/Core/Entity/EntityPublishedTrait.php b/core/lib/Drupal/Core/Entity/EntityPublishedTrait.php
index 871aceb..7b788ec 100644
--- a/core/lib/Drupal/Core/Entity/EntityPublishedTrait.php
+++ b/core/lib/Drupal/Core/Entity/EntityPublishedTrait.php
@@ -37,6 +37,7 @@ public static function publishedBaseFieldDefinitions(EntityTypeInterface $entity
       ->setDescription(new TranslatableMarkup('A boolean indicating the published state.'))
       ->setRevisionable(TRUE)
       ->setTranslatable(TRUE)
+      ->setRequired(TRUE)
       ->setDefaultValue(TRUE)];
   }
 
diff --git a/core/lib/Drupal/Core/Entity/Sql/SqlContentEntityStorageSchema.php b/core/lib/Drupal/Core/Entity/Sql/SqlContentEntityStorageSchema.php
index 807a169..d01ccda 100644
--- a/core/lib/Drupal/Core/Entity/Sql/SqlContentEntityStorageSchema.php
+++ b/core/lib/Drupal/Core/Entity/Sql/SqlContentEntityStorageSchema.php
@@ -1044,11 +1044,7 @@ protected function processRevisionTable(ContentEntityTypeInterface $entity_type,
    * @return array
    *   A partial schema array for the base table.
    */
-  protected function processDataTable(ContentEntityTypeInterface $entity_type, array &$schema) {
-    // Marking the respective fields as NOT NULL makes the indexes more
-    // performant.
-    $schema['fields'][$entity_type->getKey('default_langcode')]['not null'] = TRUE;
-  }
+  protected function processDataTable(ContentEntityTypeInterface $entity_type, array &$schema) { }
 
   /**
    * Processes the gathered schema for a base table.
@@ -1061,11 +1057,7 @@ protected function processDataTable(ContentEntityTypeInterface $entity_type, arr
    * @return array
    *   A partial schema array for the base table.
    */
-  protected function processRevisionDataTable(ContentEntityTypeInterface $entity_type, array &$schema) {
-    // Marking the respective fields as NOT NULL makes the indexes more
-    // performant.
-    $schema['fields'][$entity_type->getKey('default_langcode')]['not null'] = TRUE;
-  }
+  protected function processRevisionDataTable(ContentEntityTypeInterface $entity_type, array &$schema) { }
 
   /**
    * Processes the specified entity key.
@@ -1612,35 +1604,29 @@ protected function getSharedTableFieldSchema(FieldStorageDefinitionInterface $st
     }
 
     $field_name = $storage_definition->getName();
-    $base_table = $this->storage->getBaseTable();
+    $properties = $storage_definition->getPropertyDefinitions();
 
     // A shared table contains rows for entities where the field is empty
     // (since other fields stored in the same table might not be empty), thus
     // the only columns that can be 'not null' are those for required
-    // properties of required fields. However, even those would break in the
-    // case where a new field is added to a table that contains existing rows.
-    // For now, we only hardcode 'not null' to a couple "entity keys", in order
-    // to keep their indexes optimized.
-    // @todo Revisit once we have support for 'initial' in
-    //   https://www.drupal.org/node/2346019.
-    $not_null_keys = $this->entityType->getKeys();
-    // Label fields are not necessarily required.
-    unset($not_null_keys['label']);
+    // properties of required fields.
+    $field_storage_is_required = $storage_definition->isStorageRequired();
+
     // Because entity ID and revision ID are both serial fields in the base and
     // revision table respectively, the revision ID is not known yet, when
     // inserting data into the base table. Instead the revision ID in the base
     // table is updated after the data has been inserted into the revision
     // table. For this reason the revision ID field cannot be marked as NOT
     // NULL.
-    if ($table_name == $base_table) {
-      unset($not_null_keys['revision']);
+    if ($table_name == $this->storage->getBaseTable() && $field_name == $this->entityType->getKey('revision')) {
+      $field_storage_is_required = FALSE;
     }
 
     foreach ($column_mapping as $field_column_name => $schema_field_name) {
       $column_schema = $field_schema['columns'][$field_column_name];
 
       $schema['fields'][$schema_field_name] = $column_schema;
-      $schema['fields'][$schema_field_name]['not null'] = in_array($field_name, $not_null_keys);
+      $schema['fields'][$schema_field_name]['not null'] = $field_storage_is_required && $properties[$field_column_name]->isRequired();
     }
 
     if (!empty($field_schema['indexes'])) {
diff --git a/core/lib/Drupal/Core/Field/Plugin/Field/FieldType/LanguageItem.php b/core/lib/Drupal/Core/Field/Plugin/Field/FieldType/LanguageItem.php
index 0b9bba9..e5f3f08 100644
--- a/core/lib/Drupal/Core/Field/Plugin/Field/FieldType/LanguageItem.php
+++ b/core/lib/Drupal/Core/Field/Plugin/Field/FieldType/LanguageItem.php
@@ -2,6 +2,7 @@
 
 namespace Drupal\Core\Field\Plugin\Field\FieldType;
 
+use Drupal\Core\Field\FieldDefinitionInterface;
 use Drupal\Core\Field\FieldStorageDefinitionInterface;
 use Drupal\Core\Field\FieldItemBase;
 use Drupal\Core\Language\LanguageInterface;
@@ -117,4 +118,12 @@ public function onChange($property_name, $notify = TRUE) {
     parent::onChange($property_name, $notify);
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  public static function generateSampleValue(FieldDefinitionInterface $field_definition) {
+    $values['value'] = LanguageInterface::LANGCODE_NOT_SPECIFIED;
+    return $values;
+  }
+
 }
diff --git a/core/modules/aggregator/src/Tests/FeedParserTest.php b/core/modules/aggregator/src/Tests/FeedParserTest.php
index 6c4a04d..128ea83 100644
--- a/core/modules/aggregator/src/Tests/FeedParserTest.php
+++ b/core/modules/aggregator/src/Tests/FeedParserTest.php
@@ -85,7 +85,7 @@ public function testHtmlEntitiesSample() {
    */
   public function testRedirectFeed() {
     $redirect_url = Url::fromRoute('aggregator_test.redirect')->setAbsolute()->toString();
-    $feed = Feed::create(array('url' => $redirect_url, 'title' => $this->randomMachineName()));
+    $feed = Feed::create(array('url' => $redirect_url, 'title' => $this->randomMachineName(), 'refresh' => 900));
     $feed->save();
     $feed->refreshItems();
 
@@ -99,7 +99,7 @@ public function testRedirectFeed() {
   public function testInvalidFeed() {
     // Simulate a typo in the URL to force a curl exception.
     $invalid_url = 'http:/www.drupal.org';
-    $feed = Feed::create(array('url' => $invalid_url, 'title' => $this->randomMachineName()));
+    $feed = Feed::create(array('url' => $invalid_url, 'title' => $this->randomMachineName(), 'refresh' => 900));
     $feed->save();
 
     // Update the feed. Use the UI to be able to check the message easily.
diff --git a/core/modules/aggregator/tests/src/Kernel/AggregatorTitleTest.php b/core/modules/aggregator/tests/src/Kernel/AggregatorTitleTest.php
index 782ac6f..4c2891c 100644
--- a/core/modules/aggregator/tests/src/Kernel/AggregatorTitleTest.php
+++ b/core/modules/aggregator/tests/src/Kernel/AggregatorTitleTest.php
@@ -51,6 +51,7 @@ public function testStringFormatter() {
     $aggregator_feed = Feed::create([
       'title' => 'testing title',
       'url' => 'http://www.example.com',
+      'refresh' => 900,
     ]);
     $aggregator_feed->save();
 
diff --git a/core/modules/aggregator/tests/src/Kernel/Views/AggregatorFeedViewsFieldAccessTest.php b/core/modules/aggregator/tests/src/Kernel/Views/AggregatorFeedViewsFieldAccessTest.php
index d0ca46e..9fa4496 100644
--- a/core/modules/aggregator/tests/src/Kernel/Views/AggregatorFeedViewsFieldAccessTest.php
+++ b/core/modules/aggregator/tests/src/Kernel/Views/AggregatorFeedViewsFieldAccessTest.php
@@ -34,6 +34,7 @@ public function testAggregatorFeedFields() {
       'title' => 'Drupal org',
       'url' => 'https://www.drupal.org/rss.xml',
       'link' => 'https://www.drupal.org/rss.xml',
+      'refresh' => 900,
     ]);
     $feed->save();
 
diff --git a/core/modules/aggregator/tests/src/Kernel/Views/AggregatorItemViewsFieldAccessTest.php b/core/modules/aggregator/tests/src/Kernel/Views/AggregatorItemViewsFieldAccessTest.php
index a095d3c..e007d8e 100644
--- a/core/modules/aggregator/tests/src/Kernel/Views/AggregatorItemViewsFieldAccessTest.php
+++ b/core/modules/aggregator/tests/src/Kernel/Views/AggregatorItemViewsFieldAccessTest.php
@@ -35,6 +35,7 @@ public function testAggregatorItemFields() {
     $feed = Feed::create([
       'title' => 'Drupal org',
       'url' => 'https://www.drupal.org/rss.xml',
+      'refresh' => 900,
     ]);
     $feed->save();
     $item = Item::create([
diff --git a/core/modules/comment/tests/src/Kernel/Views/CommentLinksTest.php b/core/modules/comment/tests/src/Kernel/Views/CommentLinksTest.php
index ffb91b0..08a326d 100644
--- a/core/modules/comment/tests/src/Kernel/Views/CommentLinksTest.php
+++ b/core/modules/comment/tests/src/Kernel/Views/CommentLinksTest.php
@@ -19,6 +19,13 @@
 class CommentLinksTest extends CommentViewsKernelTestBase {
 
   /**
+   * Modules to enable.
+   *
+   * @var array
+   */
+  public static $modules = ['entity_test'];
+
+  /**
    * Views used by this test.
    *
    * @var array
@@ -26,14 +33,26 @@ class CommentLinksTest extends CommentViewsKernelTestBase {
   public static $testViews = ['test_comment'];
 
   /**
+   * {@inheritdoc}
+   */
+  protected function setUp($import_test_views = TRUE) {
+    parent::setUp($import_test_views);
+
+    $this->installEntitySchema('entity_test');
+  }
+
+  /**
    * Test the comment approve link.
    */
   public function testLinkApprove() {
+    $host = EntityTest::create(['name' => $this->randomString()]);
+    $host->save();
 
     // Create an unapproved comment.
     $comment = $this->commentStorage->create([
       'uid' => $this->adminUser->id(),
       'entity_type' => 'entity_test',
+      'entity_id' => $host->id(),
       'comment_type' => 'entity_test',
       'status' => 0,
     ]);
@@ -91,8 +110,7 @@ public function testLinkApprove() {
    * Test the comment reply link.
    */
   public function testLinkReply() {
-    $this->enableModules(['field', 'entity_test']);
-    $this->installEntitySchema('entity_test');
+    $this->enableModules(['field']);
     $this->installSchema('comment', ['comment_entity_statistics']);
     $this->installConfig(['field']);
 
diff --git a/core/modules/comment/tests/src/Kernel/Views/CommentUserNameTest.php b/core/modules/comment/tests/src/Kernel/Views/CommentUserNameTest.php
index dae2c48..92112e4 100644
--- a/core/modules/comment/tests/src/Kernel/Views/CommentUserNameTest.php
+++ b/core/modules/comment/tests/src/Kernel/Views/CommentUserNameTest.php
@@ -4,6 +4,7 @@
 
 use Drupal\comment\Entity\Comment;
 use Drupal\Core\Session\AnonymousUserSession;
+use Drupal\entity_test\Entity\EntityTest;
 use Drupal\Tests\views\Kernel\ViewsKernelTestBase;
 use Drupal\user\Entity\Role;
 use Drupal\user\Entity\User;
@@ -36,6 +37,7 @@ protected function setUp($import_test_views = TRUE) {
 
     $this->installEntitySchema('user');
     $this->installEntitySchema('comment');
+    $this->installEntitySchema('entity_test');
     // Create the anonymous role.
     $this->installConfig(['user']);
 
@@ -67,12 +69,16 @@ protected function setUp($import_test_views = TRUE) {
     ]);
     $this->adminUser->save();
 
+    $host = EntityTest::create(['name' => $this->randomString()]);
+    $host->save();
+
     // Create some comments.
     $comment = Comment::create([
       'subject' => 'My comment title',
       'uid' => $this->adminUser->id(),
       'name' => $this->adminUser->label(),
       'entity_type' => 'entity_test',
+      'entity_id' => $host->id(),
       'comment_type' => 'entity_test',
       'status' => 1,
     ]);
@@ -85,6 +91,7 @@ protected function setUp($import_test_views = TRUE) {
       'mail' => 'test@example.com',
       'homepage' => 'https://example.com',
       'entity_type' => 'entity_test',
+      'entity_id' => $host->id(),
       'comment_type' => 'entity_test',
       'created' => 123456,
       'status' => 1,
diff --git a/core/modules/comment/tests/src/Kernel/Views/CommentViewsFieldAccessTest.php b/core/modules/comment/tests/src/Kernel/Views/CommentViewsFieldAccessTest.php
index f807c58..1ca5e43 100644
--- a/core/modules/comment/tests/src/Kernel/Views/CommentViewsFieldAccessTest.php
+++ b/core/modules/comment/tests/src/Kernel/Views/CommentViewsFieldAccessTest.php
@@ -3,6 +3,7 @@
 namespace Drupal\Tests\comment\Kernel\Views;
 
 use Drupal\comment\Entity\Comment;
+use Drupal\entity_test\Entity\EntityTest;
 use Drupal\user\Entity\User;
 use Drupal\Tests\views\Kernel\Handler\FieldFieldAccessTestBase;
 
@@ -25,6 +26,7 @@ protected function setUp($import_test_views = TRUE) {
     parent::setUp($import_test_views);
 
     $this->installEntitySchema('comment');
+    $this->installEntitySchema('entity_test');
   }
 
   /**
@@ -36,10 +38,14 @@ public function testCommentFields() {
     ]);
     $user->save();
 
+    $host = EntityTest::create(['name' => $this->randomString()]);
+    $host->save();
+
     $comment = Comment::create([
       'subject' => 'My comment title',
       'uid' => $user->id(),
       'entity_type' => 'entity_test',
+      'entity_id' => $host->id(),
       'comment_type' => 'entity_test',
     ]);
     $comment->save();
@@ -51,6 +57,7 @@ public function testCommentFields() {
       'mail' => 'test@example.com',
       'homepage' => 'https://example.com',
       'entity_type' => 'entity_test',
+      'entity_id' => $host->id(),
       'comment_type' => 'entity_test',
       'created' => 123456,
       'status' => 1,
diff --git a/core/modules/content_moderation/src/Entity/ContentModerationState.php b/core/modules/content_moderation/src/Entity/ContentModerationState.php
index 6d5b39c..baafa37 100644
--- a/core/modules/content_moderation/src/Entity/ContentModerationState.php
+++ b/core/modules/content_moderation/src/Entity/ContentModerationState.php
@@ -59,14 +59,16 @@ public static function baseFieldDefinitions(EntityTypeInterface $entity_type) {
       ->setLabel(t('Workflow'))
       ->setDescription(t('The workflow the moderation state is in.'))
       ->setSetting('target_type', 'workflow')
-      ->setRequired(TRUE)
+      // @todo Make this field required in https://www.drupal.org/node/2817835.
+      //->setRequired(TRUE)
       ->setTranslatable(TRUE)
       ->setRevisionable(TRUE);
 
     $fields['moderation_state'] = BaseFieldDefinition::create('string')
       ->setLabel(t('Moderation state'))
       ->setDescription(t('The moderation state of the referenced content.'))
-      ->setRequired(TRUE)
+      // @todo Make this field required in https://www.drupal.org/node/2817835.
+      //->setRequired(TRUE)
       ->setTranslatable(TRUE)
       ->setRevisionable(TRUE);
 
diff --git a/core/modules/content_moderation/tests/src/Kernel/ContentModerationStateTest.php b/core/modules/content_moderation/tests/src/Kernel/ContentModerationStateTest.php
index 5151155..e9e33d0 100644
--- a/core/modules/content_moderation/tests/src/Kernel/ContentModerationStateTest.php
+++ b/core/modules/content_moderation/tests/src/Kernel/ContentModerationStateTest.php
@@ -90,10 +90,15 @@ public function testBasicModeration($entity_type_id) {
     $workflow->getTypePlugin()->addEntityTypeAndBundle($entity_type_id, $bundle_id);
     $workflow->save();
 
+    $entity_type = $this->entityTypeManager->getDefinition($entity_type_id);
     $entity = $entity_storage->create([
-      'title' => 'Test title',
-      $this->entityTypeManager->getDefinition($entity_type_id)->getKey('bundle') => $bundle_id,
+      $entity_type->getKey('label') => 'Test title',
+      $entity_type->getKey('bundle') => $bundle_id,
     ]);
+    // Make sure we add values for all of the required fields.
+    if ($entity_type_id == 'block_content') {
+      $entity->info = $this->randomString();
+    }
     $entity->save();
     $entity = $this->reloadEntity($entity);
     $this->assertEquals('draft', $entity->moderation_state->value);
diff --git a/core/modules/menu_link_content/src/Tests/LinksTest.php b/core/modules/menu_link_content/src/Tests/LinksTest.php
index 84fecde..8ea6519 100644
--- a/core/modules/menu_link_content/src/Tests/LinksTest.php
+++ b/core/modules/menu_link_content/src/Tests/LinksTest.php
@@ -125,6 +125,7 @@ public function testCreateLink() {
       'menu_name' => 'menu_test',
       'bundle' => 'menu_link_content',
       'link' => [['uri' => 'internal:/']],
+      'title' => 'Menu link test',
     );
     $link = MenuLinkContent::create($options);
     $link->save();
diff --git a/core/modules/menu_link_content/src/Tests/MenuLinkContentTranslationUITest.php b/core/modules/menu_link_content/src/Tests/MenuLinkContentTranslationUITest.php
index cf802b7..ab39617 100644
--- a/core/modules/menu_link_content/src/Tests/MenuLinkContentTranslationUITest.php
+++ b/core/modules/menu_link_content/src/Tests/MenuLinkContentTranslationUITest.php
@@ -70,7 +70,7 @@ public function testTranslationLinkOnMenuEditForm() {
     $this->drupalGet('admin/structure/menu/manage/tools');
     $this->assertNoLink(t('Translate'));
 
-    $menu_link_content = MenuLinkContent::create(['menu_name' => 'tools', 'link' => ['uri' => 'internal:/admin/structure/menu']]);
+    $menu_link_content = MenuLinkContent::create(['menu_name' => 'tools', 'link' => ['uri' => 'internal:/admin/structure/menu'], 'title' => 'Link test']);
     $menu_link_content->save();
     $this->drupalGet('admin/structure/menu/manage/tools');
     $this->assertLink(t('Translate'));
diff --git a/core/modules/menu_link_content/tests/src/Kernel/MenuLinkContentCacheabilityBubblingTest.php b/core/modules/menu_link_content/tests/src/Kernel/MenuLinkContentCacheabilityBubblingTest.php
index c7689d9..87d1916 100644
--- a/core/modules/menu_link_content/tests/src/Kernel/MenuLinkContentCacheabilityBubblingTest.php
+++ b/core/modules/menu_link_content/tests/src/Kernel/MenuLinkContentCacheabilityBubblingTest.php
@@ -109,6 +109,7 @@ public function testOutboundPathAndRouteProcessing() {
       $menu_link_content = MenuLinkContent::create([
         'link' => ['uri' => $expectation['uri']],
         'menu_name' => 'tools',
+        'title' => 'Link test',
       ]);
       $menu_link_content->save();
       $tree = $menu_tree->load('tools', new MenuTreeParameters());
@@ -129,6 +130,7 @@ public function testOutboundPathAndRouteProcessing() {
       $menu_link_content = MenuLinkContent::create([
         'link' => ['uri' => $expectation['uri']],
         'menu_name' => 'tools',
+        'title' => 'Link test',
       ]);
       $menu_link_content->save();
       $expected_cacheability = $expected_cacheability->merge($expectation['cacheability']);
diff --git a/core/modules/migrate/src/Plugin/migrate/destination/EntityContentBase.php b/core/modules/migrate/src/Plugin/migrate/destination/EntityContentBase.php
index 9da3de6..350370f 100644
--- a/core/modules/migrate/src/Plugin/migrate/destination/EntityContentBase.php
+++ b/core/modules/migrate/src/Plugin/migrate/destination/EntityContentBase.php
@@ -213,11 +213,10 @@ protected function processStubRow(Row $row) {
       if ($field_definition->isRequired() && is_null($row->getDestinationProperty($field_name))) {
         // Use the configured default value for this specific field, if any.
         if ($default_value = $field_definition->getDefaultValueLiteral()) {
-          $values[] = $default_value;
+          $values = reset($default_value);
         }
         else {
           // Otherwise, ask the field type to generate a sample value.
-          $field_type = $field_definition->getType();
           /** @var \Drupal\Core\Field\FieldItemInterface $field_type_class */
           $field_type_class = $this->fieldTypeManager
             ->getPluginClass($field_definition->getType());
diff --git a/core/modules/node/node.install b/core/modules/node/node.install
index 0582459..fe5a13d 100644
--- a/core/modules/node/node.install
+++ b/core/modules/node/node.install
@@ -189,7 +189,9 @@ function node_update_8002() {
   // Regenerate entity type indexes, this should drop "node__default_langcode".
   $manager->updateEntityType($manager->getEntityType('node'));
   // Regenerate "langcode" indexes, this should drop "node_field__langcode".
-  $manager->updateFieldStorageDefinition($manager->getFieldStorageDefinition('langcode', 'node'));
+  $field_definition = $manager->getFieldStorageDefinition('langcode', 'node');
+  $field_definition->setStorageRequired(TRUE);
+  $manager->updateFieldStorageDefinition($field_definition);
 }
 
 /**
@@ -253,5 +255,18 @@ function node_update_8301() {
 }
 
 /**
+ * Update the 'uid' field in order to make it required at the storage level.
+ */
+function node_update_8302() {
+  // The SQL content entity schema no longer uses entity keys to mark their
+  // corresponding fields as NOT NULL in the database, so we need to update the
+  // 'uid' field manually.
+  $definition_update_manager = \Drupal::entityDefinitionUpdateManager();
+  $field_storage_definition = $definition_update_manager->getFieldStorageDefinition('uid', 'node');
+  $field_storage_definition->setStorageRequired(TRUE);
+  $definition_update_manager->updateFieldStorageDefinition($field_storage_definition);
+}
+
+/**
  * @} End of "addtogroup updates-8.3.x".
  */
diff --git a/core/modules/node/src/Entity/Node.php b/core/modules/node/src/Entity/Node.php
index 0edb58f..bb100fc 100644
--- a/core/modules/node/src/Entity/Node.php
+++ b/core/modules/node/src/Entity/Node.php
@@ -380,6 +380,7 @@ public static function baseFieldDefinitions(EntityTypeInterface $entity_type) {
     $fields['uid'] = BaseFieldDefinition::create('entity_reference')
       ->setLabel(t('Authored by'))
       ->setDescription(t('The username of the content author.'))
+      ->setStorageRequired(TRUE)
       ->setRevisionable(TRUE)
       ->setSetting('target_type', 'user')
       ->setDefaultValueCallback('Drupal\node\Entity\Node::getCurrentUserId')
diff --git a/core/modules/node/src/NodeStorageSchema.php b/core/modules/node/src/NodeStorageSchema.php
index 18d6303..e5dd458 100644
--- a/core/modules/node/src/NodeStorageSchema.php
+++ b/core/modules/node/src/NodeStorageSchema.php
@@ -35,7 +35,7 @@ protected function getSharedTableFieldSchema(FieldStorageDefinitionInterface $st
     if ($table_name == 'node_revision') {
       switch ($field_name) {
         case 'langcode':
-          $this->addSharedTableFieldIndex($storage_definition, $schema, TRUE);
+          $this->addSharedTableFieldIndex($storage_definition, $schema);
           break;
 
         case 'revision_uid':
@@ -47,9 +47,7 @@ protected function getSharedTableFieldSchema(FieldStorageDefinitionInterface $st
     if ($table_name == 'node_field_data') {
       switch ($field_name) {
         case 'promote':
-        case 'status':
         case 'sticky':
-        case 'title':
           // Improves the performance of the indexes defined
           // in getEntitySchema().
           $schema['fields'][$field_name]['not null'] = TRUE;
diff --git a/core/modules/system/src/Tests/Entity/EntityDefinitionTestTrait.php b/core/modules/system/src/Tests/Entity/EntityDefinitionTestTrait.php
index 0123597..87efdca 100644
--- a/core/modules/system/src/Tests/Entity/EntityDefinitionTestTrait.php
+++ b/core/modules/system/src/Tests/Entity/EntityDefinitionTestTrait.php
@@ -135,14 +135,12 @@ protected function modifyBaseField() {
   }
 
   /**
-   * Promotes a field to an entity key.
+   * Makes a base field required.
    */
-  protected function makeBaseFieldEntityKey() {
-    $entity_type = clone $this->entityManager->getDefinition('entity_test_update');
-    $entity_keys = $entity_type->getKeys();
-    $entity_keys['new_base_field'] = 'new_base_field';
-    $entity_type->set('entity_keys', $entity_keys);
-    $this->state->set('entity_test_update.entity_type', $entity_type);
+  protected function makeBaseFieldRequired() {
+    $definitions = \Drupal::state()->get('entity_test_update.additional_base_field_definitions', []);
+    $definitions['new_base_field']->setRequired(TRUE);
+    $this->state->set('entity_test_update.additional_base_field_definitions', $definitions);
   }
 
   /**
diff --git a/core/modules/system/src/Tests/Update/EntityUpdateTest.php b/core/modules/system/src/Tests/Update/EntityUpdateTest.php
index 6328f58..8a10b3f 100644
--- a/core/modules/system/src/Tests/Update/EntityUpdateTest.php
+++ b/core/modules/system/src/Tests/Update/EntityUpdateTest.php
@@ -21,9 +21,9 @@ protected function setDatabaseDumpFiles() {
   }
 
   /**
-   * Tests system_update_8302().
+   * Tests system_update_8203().
    */
-  public function testSystemUpdate8302() {
+  public function testSystemUpdate8203() {
     // The installed field storage schema is wrong before running the update.
     $key_value_store = \Drupal::keyValue('entity.storage_schema.sql');
     $id_schema = $key_value_store->get('node.field_schema_data.nid', []);
diff --git a/core/modules/system/system.install b/core/modules/system/system.install
index 019abd9..c6aed42 100644
--- a/core/modules/system/system.install
+++ b/core/modules/system/system.install
@@ -14,6 +14,7 @@
 use Drupal\Core\Database\Database;
 use Drupal\Core\DrupalKernel;
 use Drupal\Core\Entity\Sql\SqlEntityStorageInterface;
+use Drupal\Core\Field\BaseFieldDefinition;
 use Drupal\Core\Site\Settings;
 use Drupal\Core\StreamWrapper\PrivateStream;
 use Drupal\Core\StreamWrapper\PublicStream;
@@ -1089,6 +1090,18 @@ function system_schema() {
 }
 
 /**
+ * Implements hook_update_dependencies().
+ */
+function system_update_dependencies() {
+  // system_update_8302() has to run after the 'status' field was made an entity
+  // key for the Comment entity type.
+  $dependencies['system'][8302] = array(
+    'comment' => 8301,
+  );
+  return $dependencies;
+}
+
+/**
  * @addtogroup updates-8.0.0-beta
  * @{
  */
@@ -1833,7 +1846,7 @@ function system_update_8301() {
 }
 
 /**
- * Correct the last installed storage schema for all ID and revision fields.
+ * Correct the installed schema and NOT NULL handling for required base fields.
  */
 function system_update_8302() {
   $entity_type_manager = \Drupal::entityTypeManager();
@@ -1841,16 +1854,35 @@ function system_update_8302() {
   /** @var \Drupal\Core\Entity\EntityLastInstalledSchemaRepositoryInterface $entity_last_installed_schema_respository */
   $entity_last_installed_schema_respository = \Drupal::service('entity.last_installed_schema.repository');
 
-  foreach ($entity_type_manager->getDefinitions() as $entity_type_id => $entity_type) {
+  foreach ($entity_type_manager->getDefinitions() as $entity_type_id => $entityType) {
+    $original_entity_type = $entity_last_installed_schema_respository->getLastInstalledDefinition($entity_type_id);
     $storage = $entity_type_manager->getStorage($entity_type_id);
     if ($storage instanceof SqlEntityStorageInterface) {
-      $field_names_to_update = [$entity_type->getKey('id')];
-      if ($entity_type->isRevisionable()) {
-        $field_names_to_update[] = $entity_type->getKey('revision');
-      }
       foreach ($entity_last_installed_schema_respository->getLastInstalledFieldStorageDefinitions($entity_type_id) as $field_name => $field_definition) {
-        if (in_array($field_definition->getName(), $field_names_to_update)) {
-          $definition_update_manager->updateFieldStorageDefinition($field_definition);
+        /** @var \Drupal\Core\Field\BaseFieldDefinition $field_definition */
+        if ($field_definition instanceof BaseFieldDefinition) {
+          $field_name = $field_definition->getName();
+
+          // The SQL content entity schema no longer uses entity keys to mark
+          // their corresponding fields as NOT NULL in the database, so we need
+          // to update them manually.
+          $entity_keys_names = [
+            $original_entity_type->getKey('id'),
+            $original_entity_type->getKey('uuid'),
+            $original_entity_type->getKey('revision'),
+            $original_entity_type->getKey('langcode'),
+          ];
+          if (in_array($field_name, $entity_keys_names)) {
+            $field_definition->setStorageRequired(TRUE);
+          }
+
+          if ($field_name == $original_entity_type->getKey('published')) {
+            $field_definition->setRequired(TRUE);
+          }
+
+          if ($field_definition->isStorageRequired()) {
+            $definition_update_manager->updateFieldStorageDefinition($field_definition);
+          }
         }
       }
     }
diff --git a/core/modules/system/tests/modules/entity_test/src/Entity/EntityTestMulRevChanged.php b/core/modules/system/tests/modules/entity_test/src/Entity/EntityTestMulRevChanged.php
index 3913075..a3fb47e 100644
--- a/core/modules/system/tests/modules/entity_test/src/Entity/EntityTestMulRevChanged.php
+++ b/core/modules/system/tests/modules/entity_test/src/Entity/EntityTestMulRevChanged.php
@@ -58,6 +58,7 @@ public static function baseFieldDefinitions(EntityTypeInterface $entity_type) {
       ->setLabel(t('Revision ID'))
       ->setDescription(t('The version id of the test entity.'))
       ->setReadOnly(TRUE)
+      ->setStorageRequired(TRUE)
       ->setSetting('unsigned', TRUE);
 
     $fields['revision_translation_affected'] = BaseFieldDefinition::create('boolean')
diff --git a/core/modules/user/src/UserStorageSchema.php b/core/modules/user/src/UserStorageSchema.php
index c8c3e46..9ebf15c 100644
--- a/core/modules/user/src/UserStorageSchema.php
+++ b/core/modules/user/src/UserStorageSchema.php
@@ -44,9 +44,6 @@ protected function getSharedTableFieldSchema(FieldStorageDefinitionInterface $st
     if ($table_name == 'users_field_data') {
       switch ($field_name) {
         case 'name':
-          // Improves the performance of the user__name index defined
-          // in getEntitySchema().
-          $schema['fields'][$field_name]['not null'] = TRUE;
           // Make sure the field is no longer than 191 characters so we can
           // add a unique constraint in MySQL.
           $schema['fields'][$field_name]['length'] = USERNAME_MAX_LENGTH;
diff --git a/core/tests/Drupal/KernelTests/Core/Entity/EntityDefinitionUpdateTest.php b/core/tests/Drupal/KernelTests/Core/Entity/EntityDefinitionUpdateTest.php
index e716b70..ebfe35b 100644
--- a/core/tests/Drupal/KernelTests/Core/Entity/EntityDefinitionUpdateTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Entity/EntityDefinitionUpdateTest.php
@@ -765,9 +765,9 @@ public function testBaseFieldEntityKeyUpdateWithExistingData() {
     $entity = $this->entityManager->getStorage('entity_test_update')->create();
     $entity->save();
 
-    // Promote the base field to an entity key. This will trigger the addition
-    // of a NOT NULL constraint.
-    $this->makeBaseFieldEntityKey();
+    // Make the base field required. This will trigger the addition of a NOT
+    // NULL constraint.
+    $this->makeBaseFieldRequired();
 
     // Try to apply the update and verify they fail since we have a NULL value.
     $message = 'An error occurs when trying to enabling NOT NULL constraints with NULL data.';
diff --git a/core/tests/Drupal/KernelTests/Core/Menu/MenuLinkTreeTest.php b/core/tests/Drupal/KernelTests/Core/Menu/MenuLinkTreeTest.php
index 1efb14b..3a440da 100644
--- a/core/tests/Drupal/KernelTests/Core/Menu/MenuLinkTreeTest.php
+++ b/core/tests/Drupal/KernelTests/Core/Menu/MenuLinkTreeTest.php
@@ -62,9 +62,9 @@ public function testDeleteLinksInMenu() {
     \Drupal::entityManager()->getStorage('menu')->create(array('id' => 'menu1'))->save();
     \Drupal::entityManager()->getStorage('menu')->create(array('id' => 'menu2'))->save();
 
-    \Drupal::entityManager()->getStorage('menu_link_content')->create(array('link' => ['uri' => 'internal:/menu_name_test'], 'menu_name' => 'menu1', 'bundle' => 'menu_link_content'))->save();
-    \Drupal::entityManager()->getStorage('menu_link_content')->create(array('link' => ['uri' => 'internal:/menu_name_test'], 'menu_name' => 'menu1', 'bundle' => 'menu_link_content'))->save();
-    \Drupal::entityManager()->getStorage('menu_link_content')->create(array('link' => ['uri' => 'internal:/menu_name_test'], 'menu_name' => 'menu2', 'bundle' => 'menu_link_content'))->save();
+    \Drupal::entityManager()->getStorage('menu_link_content')->create(array('link' => ['uri' => 'internal:/menu_name_test'], 'menu_name' => 'menu1', 'bundle' => 'menu_link_content', 'title' => 'Link test'))->save();
+    \Drupal::entityManager()->getStorage('menu_link_content')->create(array('link' => ['uri' => 'internal:/menu_name_test'], 'menu_name' => 'menu1', 'bundle' => 'menu_link_content', 'title' => 'Link test'))->save();
+    \Drupal::entityManager()->getStorage('menu_link_content')->create(array('link' => ['uri' => 'internal:/menu_name_test'], 'menu_name' => 'menu2', 'bundle' => 'menu_link_content', 'title' => 'Link test'))->save();
 
     $output = $this->linkTree->load('menu1', new MenuTreeParameters());
     $this->assertEqual(count($output), 2);
diff --git a/core/tests/Drupal/Tests/Core/Entity/Sql/SqlContentEntityStorageSchemaTest.php b/core/tests/Drupal/Tests/Core/Entity/Sql/SqlContentEntityStorageSchemaTest.php
index b0f2948..dd55888 100644
--- a/core/tests/Drupal/Tests/Core/Entity/Sql/SqlContentEntityStorageSchemaTest.php
+++ b/core/tests/Drupal/Tests/Core/Entity/Sql/SqlContentEntityStorageSchemaTest.php
@@ -74,6 +74,7 @@ protected function setUp() {
       'columns' => array(
         'value' => array(
           'type' => 'int',
+          'not null' => TRUE,
         ),
       ),
     ));
@@ -500,6 +501,7 @@ public function testGetSchemaTranslatable() {
       'columns' => array(
         'value' => array(
           'type' => 'varchar',
+          'not null' => TRUE,
         ),
       ),
     ));
@@ -509,6 +511,7 @@ public function testGetSchemaTranslatable() {
         'value' => array(
           'type' => 'int',
           'size' => 'tiny',
+          'not null' => TRUE,
         ),
       ),
     ));
@@ -618,6 +621,7 @@ public function testGetSchemaRevisionableTranslatable() {
       'columns' => array(
         'value' => array(
           'type' => 'int',
+          'not null' => TRUE,
         ),
       ),
     ));
@@ -625,6 +629,7 @@ public function testGetSchemaRevisionableTranslatable() {
       'columns' => array(
         'value' => array(
           'type' => 'varchar',
+          'not null' => TRUE,
         ),
       ),
     ));
@@ -633,6 +638,7 @@ public function testGetSchemaRevisionableTranslatable() {
         'value' => array(
           'type' => 'int',
           'size' => 'tiny',
+          'not null' => TRUE,
         ),
       ),
     ));
@@ -1403,6 +1409,9 @@ public function setUpStorageDefinition($field_name, array $schema) {
     $this->storageDefinitions[$field_name]->expects($this->any())
       ->method('getColumns')
       ->will($this->returnValue($schema['columns']));
+    $this->storageDefinitions[$field_name]->expects($this->any())
+      ->method('isStorageRequired')
+      ->will($this->returnValue(TRUE));
     // Add property definitions.
     if (!empty($schema['columns'])) {
       $property_definitions = array();
diff --git a/core/tests/Drupal/Tests/Core/Entity/Sql/SqlContentEntityStorageTest.php b/core/tests/Drupal/Tests/Core/Entity/Sql/SqlContentEntityStorageTest.php
index 5d56929..b287f75 100644
--- a/core/tests/Drupal/Tests/Core/Entity/Sql/SqlContentEntityStorageTest.php
+++ b/core/tests/Drupal/Tests/Core/Entity/Sql/SqlContentEntityStorageTest.php
@@ -298,9 +298,6 @@ public function testOnEntityTypeCreate() {
       ->method('getSchema')
       ->will($this->returnValue(array('columns' => $columns)));
 
-    $this->entityType->expects($this->once())
-      ->method('getKeys')
-      ->will($this->returnValue(array('id' => 'id')));
     $this->entityType->expects($this->any())
       ->method('getKey')
       ->will($this->returnValueMap(array(
diff --git a/core/tests/Drupal/Tests/Core/Field/TestBaseFieldDefinitionInterface.php b/core/tests/Drupal/Tests/Core/Field/TestBaseFieldDefinitionInterface.php
index 953c902..afd19f7 100644
--- a/core/tests/Drupal/Tests/Core/Field/TestBaseFieldDefinitionInterface.php
+++ b/core/tests/Drupal/Tests/Core/Field/TestBaseFieldDefinitionInterface.php
@@ -4,9 +4,10 @@
 
 use Drupal\Core\Field\FieldDefinitionInterface;
 use Drupal\Core\Field\FieldStorageDefinitionInterface;
+use Drupal\Core\Field\RequiredFieldStorageDefinitionInterface;
 
 /**
  * Defines a test interface to mock entity base field definitions.
  */
-interface TestBaseFieldDefinitionInterface extends FieldDefinitionInterface, FieldStorageDefinitionInterface {
+interface TestBaseFieldDefinitionInterface extends FieldDefinitionInterface, FieldStorageDefinitionInterface, RequiredFieldStorageDefinitionInterface {
 }