diff --git a/core/lib/Drupal/Core/Entity/EntityTypeListener.php b/core/lib/Drupal/Core/Entity/EntityTypeListener.php
index 6706fef..c8b23f6 100644
--- a/core/lib/Drupal/Core/Entity/EntityTypeListener.php
+++ b/core/lib/Drupal/Core/Entity/EntityTypeListener.php
@@ -128,11 +128,13 @@ public function onEntityTypeSchemaUpdate(EntityTypeInterface $entity_type, Entit
       $storage->onEntityTypeSchemaUpdate($entity_type, $original, $field_storage_definitions, $original_field_storage_definitions, $sandbox);
     }
 
-    $this->eventDispatcher->dispatch(EntityTypeEvents::UPDATE, new EntityTypeEvent($entity_type, $original));
+    if ($sandbox === NULL || (isset($sandbox['#finished']) && $sandbox['#finished'] === 1)) {
+      $this->eventDispatcher->dispatch(EntityTypeEvents::UPDATE, new EntityTypeEvent($entity_type, $original));
 
-    $this->entityLastInstalledSchemaRepository->setLastInstalledDefinition($entity_type);
-    if ($entity_type->entityClassImplements(FieldableEntityInterface::class)) {
-      $this->entityLastInstalledSchemaRepository->setLastInstalledFieldStorageDefinitions($entity_type_id, $field_storage_definitions);
+      $this->entityLastInstalledSchemaRepository->setLastInstalledDefinition($entity_type);
+      if ($entity_type->entityClassImplements(FieldableEntityInterface::class)) {
+        $this->entityLastInstalledSchemaRepository->setLastInstalledFieldStorageDefinitions($entity_type_id, $field_storage_definitions);
+      }
     }
   }
 
diff --git a/core/lib/Drupal/Core/Entity/EntityTypeSchemaListenerTrait.php b/core/lib/Drupal/Core/Entity/EntityTypeSchemaListenerTrait.php
index bd87146..d22ca35 100644
--- a/core/lib/Drupal/Core/Entity/EntityTypeSchemaListenerTrait.php
+++ b/core/lib/Drupal/Core/Entity/EntityTypeSchemaListenerTrait.php
@@ -25,14 +25,20 @@ public function onEntityTypeSchemaUpdate(EntityTypeInterface $entity_type, Entit
       $this->preUpdateEntityTypeSchema($entity_type, $original, $field_storage_definitions, $original_field_storage_definitions, $sandbox);
     }
 
-    // Copy data.
+    // Copy data from the original storage to the temporary one.
     if ($sandbox['original_storage']->hasData()) {
       $this->copyData($entity_type, $original, $sandbox);
     }
+    else {
+      // If there is no existing data, we still need to run the
+      // post-schema-update tasks.
+      $sandbox['#finished'] = 1;
+    }
 
     // If the data copying has finished successfully, allow the storage schema
-    // to do any required cleanup tasks.
-    if ($sandbox['#finished'] == 1) {
+    // to do any required cleanup tasks. For example, this process should take
+    // care of transforming the temporary storage into the current storage.
+    if ($sandbox['#finished'] === 1) {
       $this->postUpdateEntityTypeSchema($entity_type, $original, $field_storage_definitions, $original_field_storage_definitions, $sandbox);
     }
   }
@@ -88,41 +94,70 @@ protected function copyData(EntityTypeInterface $entity_type, EntityTypeInterfac
     $id_key = $entity_type->getKey('id');
     $revision_id_key = $entity_type->getKey('revision');
     $revision_default_key = $entity_type->getRevisionMetadataKey('revision_default');
+    $langcode_key = $entity_type->getKey('langcode');
+    $default_langcode_key = $entity_type->getKey('default_langcode');
     $revision_translation_affected_key = $entity_type->getKey('revision_translation_affected');
 
     $temporary_storage = $sandbox['temporary_storage'];
     $original_storage = $sandbox['original_storage'];
 
+    // If both the original entity type and the updated one are revisionable, we
+    // need to handle all their revisions.
+    $load_revisions = $original->isRevisionable() && $entity_type->isRevisionable();
+
     // If 'progress' is not set, then this will be the first run of the batch.
     if (!isset($sandbox['progress'])) {
       $sandbox['progress'] = 0;
       $sandbox['current_id'] = 0;
-      $sandbox['max'] = (int) $original_storage->getQuery()->count()->execute();
+      if ($load_revisions) {
+        $sandbox['max'] = (int) $original_storage->getQuery()->allRevisions()->count()->execute();
+      }
+      else {
+        $sandbox['max'] = (int) $original_storage->getQuery()->count()->execute();
+      }
     }
 
-    // Get the next entity IDs to migrate.
+    // Get the next entity identifiers to migrate.
     $step_size = Settings::get('entity_update_batch_size', 50);
-    $entity_ids = $original_storage->getQuery()
-      ->condition($id_key, $sandbox['current_id'], '>')
-      ->sort($id_key, 'ASC')
+    $query = $original_storage->getQuery();
+    if ($load_revisions) {
+      $query->allRevisions();
+      $identifier_field = $revision_id_key;
+    }
+    else {
+      $identifier_field = $id_key;
+    }
+    $entity_identifiers = $query
+      ->condition($identifier_field, $sandbox['current_id'], '>')
+      ->sort($identifier_field, 'ASC')
       ->range(0, $step_size)
       ->execute();
 
-    $entities = $original_storage->loadMultiple($entity_ids);
+    $entities = $load_revisions ? $original_storage->loadMultipleRevisions(array_keys($entity_identifiers)) : $original_storage->loadMultiple($entity_identifiers);
     foreach ($entities as $entity_id => $entity) {
       try {
-        // @todo Only set the fields needed based on the type of the conversion.
-        // Set the revision ID to be same as the entity ID.
-        $entity->set($revision_id_key, $entity_id);
+        if (!$original->isRevisionable() && $entity_type->isRevisionable()) {
+          // Set the revision ID to be same as the entity ID.
+          $entity->set($revision_id_key, $entity_id);
 
-        // We had no revisions so far, so the existing data belongs to the
-        // default revision now.
-        $entity->set($revision_default_key, TRUE);
+          // We had no revisions so far, so the existing data belongs to the
+          // default revision now.
+          $entity->set($revision_default_key, TRUE);
+        }
+
+        // Set the 'langcode' and 'default_langcode' values as needed.
+        if (!$original->isTranslatable() && $entity_type->isTranslatable()) {
+          $original_has_langcode = $entity->hasField($langcode_key) && !$entity->get($langcode_key)->isEmpty();
+          $langcode = $original_has_langcode ? $entity->get($langcode_key) : \Drupal::languageManager()->getDefaultLanguage()->getId();
+
+          $entity->set($langcode_key, $langcode);
+          $entity->set($default_langcode_key, $langcode);
+        }
 
         // Set the 'revision_translation_affected' flag to TRUE to match the
         // previous API return value: if the field was not defined the value
         // returned was always TRUE.
-        if ($entity_type->isTranslatable()) {
+        if (!$original->isRevisionable() && !$original->isTranslatable() && $entity_type->isRevisionable() && $entity_type->isTranslatable()) {
           $entity->set($revision_translation_affected_key, TRUE);
         }
 
@@ -146,7 +181,12 @@ protected function copyData(EntityTypeInterface $entity_type, EntityTypeInterfac
 
     // If we're not in maintenance mode, the number of entities could change at
     // any time so make sure that we always use the latest record count.
-    $sandbox['max'] = (int) $original_storage->getQuery()->count()->execute();
+    if ($load_revisions) {
+      $sandbox['max'] = (int) $original_storage->getQuery()->allRevisions()->count()->execute();
+    }
+    else {
+      $sandbox['max'] = (int) $original_storage->getQuery()->count()->execute();
+    }
 
     $sandbox['#finished'] = empty($sandbox['max']) ? 1 : ($sandbox['progress'] / $sandbox['max']);
   }