diff --git a/core/lib/Drupal/Core/Config/BatchConfigImporter.php b/core/lib/Drupal/Core/Config/BatchConfigImporter.php
index 67aee13..a57a076 100644
--- a/core/lib/Drupal/Core/Config/BatchConfigImporter.php
+++ b/core/lib/Drupal/Core/Config/BatchConfigImporter.php
@@ -108,7 +108,9 @@ public function processConfigurationBatch(array &$context) {
     }
     $operation = $this->getNextConfigurationOperation();
     if (!empty($operation)) {
-      $this->processConfiguration($operation['op'], $operation['name']);
+      if ($this->checkOp($operation['op'], $operation['name'])) {
+        $this->processConfiguration($operation['op'], $operation['name']);
+      }
       $context['message'] = t('Synchronizing configuration: @op @name.', array('@op' => $operation['op'], '@name' => $operation['name']));
       $processed_count = count($this->processedConfiguration['create']) + count($this->processedConfiguration['delete']) + count($this->processedConfiguration['update']);
       $context['finished'] = $processed_count / $this->totalConfigurationToProcess;
diff --git a/core/lib/Drupal/Core/Config/ConfigImporter.php b/core/lib/Drupal/Core/Config/ConfigImporter.php
index 1303b7f..9ddbfb0 100644
--- a/core/lib/Drupal/Core/Config/ConfigImporter.php
+++ b/core/lib/Drupal/Core/Config/ConfigImporter.php
@@ -14,6 +14,7 @@
 use Drupal\Core\DependencyInjection\DependencySerialization;
 use Drupal\Core\Entity\EntityStorageException;
 use Drupal\Core\Lock\LockBackendInterface;
+use Drupal\Core\StringTranslation\TranslationManager;
 use Symfony\Component\EventDispatcher\EventDispatcherInterface;
 
 /**
@@ -120,6 +121,13 @@ class ConfigImporter extends DependencySerialization {
   protected $themeHandler;
 
   /**
+   * The string translation service.
+   *
+   * @var \Drupal\Core\StringTranslation\TranslationManager
+   */
+  protected $translationManager;
+
+  /**
    * Flag set to import system.theme during processing theme enable and disables.
    *
    * @var bool
@@ -127,6 +135,13 @@ class ConfigImporter extends DependencySerialization {
   protected $processedSystemTheme = FALSE;
 
   /**
+   * List of errors that were logged during a config import.
+   *
+   * @var array
+   */
+  protected $errors = array();
+
+  /**
    * Constructs a configuration import object.
    *
    * @param \Drupal\Core\Config\StorageComparerInterface $storage_comparer
@@ -144,8 +159,10 @@ class ConfigImporter extends DependencySerialization {
    *   The module handler
    * @param \Drupal\Core\Extension\ThemeHandlerInterface $theme_handler
    *   The theme handler
+   * @param \Drupal\Core\StringTranslation\TranslationManager $translation_manager
+   *   The string translation service.
    */
-  public function __construct(StorageComparerInterface $storage_comparer, EventDispatcherInterface $event_dispatcher, ConfigManagerInterface $config_manager, LockBackendInterface $lock, TypedConfigManagerInterface $typed_config, ModuleHandlerInterface $module_handler, ThemeHandlerInterface $theme_handler) {
+  public function __construct(StorageComparerInterface $storage_comparer, EventDispatcherInterface $event_dispatcher, ConfigManagerInterface $config_manager, LockBackendInterface $lock, TypedConfigManagerInterface $typed_config, ModuleHandlerInterface $module_handler, ThemeHandlerInterface $theme_handler, TranslationManager $translation_manager) {
     $this->storageComparer = $storage_comparer;
     $this->eventDispatcher = $event_dispatcher;
     $this->configManager = $config_manager;
@@ -153,11 +170,32 @@ public function __construct(StorageComparerInterface $storage_comparer, EventDis
     $this->typedConfigManager = $typed_config;
     $this->moduleHandler = $module_handler;
     $this->themeHandler = $theme_handler;
+    $this->translationManager = $translation_manager;
     $this->processedConfiguration = $this->storageComparer->getEmptyChangelist();
     $this->processedExtensions = $this->getEmptyExtensionsProcessedList();
   }
 
   /**
+   * Logs an error message.
+   *
+   * @param string $message
+   *   The message to log.
+   */
+  protected function logError($message) {
+    $this->errors[] = $message;
+  }
+
+  /**
+   * Returns error messages created while running the import.
+   *
+   * @return array
+   *   List of messages.
+   */
+  public function getErrors() {
+    return $this->errors;
+  }
+
+  /**
    * Gets the configuration storage comparer.
    *
    * @return \Drupal\Core\Config\StorageComparerInterface
@@ -415,7 +453,9 @@ public function import() {
       // to handle dependencies correctly.
       foreach (array('delete', 'create', 'update') as $op) {
         foreach ($this->getUnprocessedConfiguration($op) as $name) {
-          $this->processConfiguration($op, $name);
+          if ($this->checkOp($op, $name)) {
+            $this->processConfiguration($op, $name);
+          }
         }
       }
       // Allow modules to react to a import.
@@ -452,10 +492,23 @@ public function validate() {
    *   The change operation.
    * @param string $name
    *   The name of the configuration to process.
+   *
+   * @throws \Exception
+   *   Thrown when the import process fails, only thrown when no importer log is
+   *   set, otherwise the exception message is logged and the configuration
+   *   is skipped.
    */
   protected function processConfiguration($op, $name) {
-    if (!$this->importInvokeOwner($op, $name)) {
-      $this->importConfig($op, $name);
+    try {
+      if (!$this->importInvokeOwner($op, $name)) {
+        $this->importConfig($op, $name);
+      }
+    }
+    catch (\Exception $e) {
+      $this->logError($this->t('Unexpected error during import with operation @op for @name: @message', array('@op' => $op, '@name' => $name, '@message' => $e->getMessage())));
+      // Error for that operation was logged, mark it as processed so that
+      // the import can continue.
+      $this->setProcessedConfiguration($op, $name);
     }
   }
 
@@ -506,6 +559,68 @@ protected function processExtension($type, $op, $name) {
   }
 
   /**
+   * Checks that the operation is still valid.
+   *
+   * During a configuration import secondary writes and deletes are possible.
+   * This method checks that the operation is still valid before processing a
+   * configuration change.
+   *
+   * @param string $op
+   *   The change operation.
+   * @param string $name
+   *   The name of the configuration to process.
+   *
+   * @throws \Drupal\Core\Config\ConfigImporterException
+   *
+   * @return bool
+   *   TRUE is to continue processing, FALSE otherwise.
+   */
+  protected function checkOp($op, $name) {
+    $target_exists = $this->storageComparer->getTargetStorage()->exists($name);
+    switch ($op) {
+      case 'delete':
+        if (!$target_exists) {
+          // The configuration has already been deleted. For example, a field
+          // is automatically deleted if all the instances are.
+          $this->setProcessedConfiguration($op, $name);
+          return FALSE;
+        }
+        break;
+
+      case 'create':
+        if ($target_exists) {
+          // If the target already exists, use the entity storage to delete it
+          // again, if is a simple config, delete it directly.
+          if ($entity_type_id = $this->configManager->getEntityTypeIdByName($name)) {
+            $entity_storage = $this->configManager->getEntityManager()->getStorage($entity_type_id);
+            $entity_type = $this->configManager->getEntityManager()->getDefinition($entity_type_id);
+            $entity = $entity_storage->load($entity_storage->getIDFromConfigName($name, $entity_type->getConfigPrefix()));
+            $entity->delete();
+            $this->logError($this->translationManager->translate('Deleted and replaced configuration entity "@name"', array('@name' => $name)));
+          }
+          else {
+            $this->storageComparer->getTargetStorage()->delete($name);
+            $this->logError($this->t('Deleted and replaced configuration "@name"', array('@name' => $name)));
+          }
+          return TRUE;
+        }
+        break;
+
+      case 'update':
+        if (!$target_exists) {
+          $this->logError($this->t('Update target "@name" is missing.', array('@name' => $name)));
+          // Mark as processed so that the synchronisation continues. Once the
+          // the current synchronisation is complete it will show up as a
+          // create.
+          $this->setProcessedConfiguration($op, $name);
+          return FALSE;
+        }
+        break;
+    }
+    return TRUE;
+  }
+
+  /**
    * Writes a configuration change from the source to the target storage.
    *
    * @param string $op
@@ -574,7 +689,6 @@ protected function importInvokeOwner($op, $name) {
       $this->setProcessedConfiguration($op, $name);
       return TRUE;
     }
-    return FALSE;
   }
 
   /**
@@ -656,5 +770,31 @@ protected function reInjectMe() {
     $this->typedConfigManager = \Drupal::service('config.typed');
     $this->moduleHandler = \Drupal::moduleHandler();
     $this->themeHandler = \Drupal::service('theme_handler');
+    $this->translationManager = \Drupal::service('string_translation');
+  }
+
+  /**
+   * Translates a string to the current language or to a given language.
+   *
+   * @param string $string
+   *   A string containing the English string to translate.
+   * @param array $args
+   *   An associative array of replacements to make after translation. Based
+   *   on the first character of the key, the value is escaped and/or themed.
+   *   See \Drupal\Component\Utility\String::format() for details.
+   * @param array $options
+   *   An associative array of additional options, with the following elements:
+   *   - 'langcode': The language code to translate to a language other than
+   *      what is used to display the page.
+   *   - 'context': The context the source string belongs to.
+   *
+   * @return string
+   *   The translated string.
+   *
+   * @see \Drupal\Core\StringTranslation\TranslationManager::translate()
+   */
+  protected function t($string, array $args = array(), array $options = array()) {
+    return $this->translationManager->translate($string, $args, $options);
   }
+
 }
diff --git a/core/lib/Drupal/Core/Config/Entity/ConfigEntityStorage.php b/core/lib/Drupal/Core/Config/Entity/ConfigEntityStorage.php
index 2d773dc..a5d634c 100644
--- a/core/lib/Drupal/Core/Config/Entity/ConfigEntityStorage.php
+++ b/core/lib/Drupal/Core/Config/Entity/ConfigEntityStorage.php
@@ -9,6 +9,7 @@
 
 use Drupal\Component\Utility\String;
 use Drupal\Core\Config\ConfigFactoryInterface;
+use Drupal\Core\Config\ConfigImporterException;
 use Drupal\Core\Entity\EntityInterface;
 use Drupal\Core\Entity\EntityMalformedException;
 use Drupal\Core\Entity\EntityStorageBase;
@@ -425,6 +426,9 @@ public function importCreate($name, Config $new_config, Config $old_config) {
   public function importUpdate($name, Config $new_config, Config $old_config) {
     $id = static::getIDFromConfigName($name, $this->entityType->getConfigPrefix());
     $entity = $this->load($id);
+    if (!$entity) {
+      throw new ConfigImporterException(String::format('Attempt to update non-existing entity "@id".', array('@id' => $id)));
+    }
     $entity->setSyncing(TRUE);
     $entity->original = clone $entity;
 
diff --git a/core/lib/Drupal/Core/Config/Entity/ImportableEntityStorageInterface.php b/core/lib/Drupal/Core/Config/Entity/ImportableEntityStorageInterface.php
index 6aca4df..4eae41e 100644
--- a/core/lib/Drupal/Core/Config/Entity/ImportableEntityStorageInterface.php
+++ b/core/lib/Drupal/Core/Config/Entity/ImportableEntityStorageInterface.php
@@ -38,6 +38,9 @@ public function importCreate($name, Config $new_config, Config $old_config);
    *   A configuration object containing the new configuration data.
    * @param \Drupal\Core\Config\Config $old_config
    *   A configuration object containing the old configuration data.
+   *
+   * @throws \Drupal\Core\Config\ConfigImporterException
+   *   Thrown when the config entity that should be updated can not be found.
    */
   public function importUpdate($name, Config $new_config, Config $old_config);
 
diff --git a/core/modules/block/custom_block/lib/Drupal/custom_block/Entity/CustomBlockType.php b/core/modules/block/custom_block/lib/Drupal/custom_block/Entity/CustomBlockType.php
index e8eee2e..de4a109 100644
--- a/core/modules/block/custom_block/lib/Drupal/custom_block/Entity/CustomBlockType.php
+++ b/core/modules/block/custom_block/lib/Drupal/custom_block/Entity/CustomBlockType.php
@@ -75,7 +75,7 @@ class CustomBlockType extends ConfigEntityBase implements CustomBlockTypeInterfa
   public function postSave(EntityStorageInterface $storage, $update = TRUE) {
     parent::postSave($storage, $update);
 
-    if (!$update) {
+    if (!$update && !$this->isSyncing()) {
       entity_invoke_bundle_hook('create', 'custom_block', $this->id());
       if (!$this->isSyncing()) {
         custom_block_add_body_field($this->id);
diff --git a/core/modules/config/lib/Drupal/config/Form/ConfigSync.php b/core/modules/config/lib/Drupal/config/Form/ConfigSync.php
index c48a776..907340c 100644
--- a/core/modules/config/lib/Drupal/config/Form/ConfigSync.php
+++ b/core/modules/config/lib/Drupal/config/Form/ConfigSync.php
@@ -250,7 +250,8 @@ public function submitForm(array &$form, array &$form_state) {
       $this->lock,
       $this->typedConfigManager,
       $this->moduleHandler,
-      $this->themeHandler
+      $this->themeHandler,
+      $this->translationManager()
     );
     if ($config_importer->alreadyImporting()) {
       drupal_set_message($this->t('Another request may be synchronizing configuration already.'));
@@ -289,6 +290,12 @@ public static function processBatch(BatchConfigImporter $config_importer, $opera
 
     $config_importer = $context['sandbox']['config_importer'];
     $config_importer->$operation($context);
+    if ($errors = $config_importer->getErrors()) {
+      if (!isset($context['results']['errors'])) {
+        $context['results']['errors'] = array();
+      }
+      $context['results']['errors'] += $errors;
+    }
   }
 
   /**
@@ -299,7 +306,16 @@ public static function processBatch(BatchConfigImporter $config_importer, $opera
    */
   public static function finishBatch($success, $results, $operations) {
     if ($success) {
-      drupal_set_message(\Drupal::translation()->translate('The configuration was imported successfully.'));
+      if (!empty($results['errors'])) {
+        foreach ($results['errors'] as $error) {
+          drupal_set_message($error, 'error');
+          watchdog('config_sync', $error, NULL, WATCHDOG_ERROR);
+        }
+        drupal_set_message(\Drupal::translation()->translate('The configuration was imported with errors.'), 'warning');
+      }
+      else {
+        drupal_set_message(\Drupal::translation()->translate('The configuration was imported successfully.'));
+      }
     }
     else {
       // An error occurred.
diff --git a/core/modules/config/lib/Drupal/config/Tests/ConfigImportAllTest.php b/core/modules/config/lib/Drupal/config/Tests/ConfigImportAllTest.php
index 038e318..2d08077 100644
--- a/core/modules/config/lib/Drupal/config/Tests/ConfigImportAllTest.php
+++ b/core/modules/config/lib/Drupal/config/Tests/ConfigImportAllTest.php
@@ -95,6 +95,9 @@ public function testInstallUninstall() {
     // Import the configuration thereby re-installing all the modules.
     $this->configImporter()->import();
 
+    // Check that there are no errors.
+    $this->assertIdentical($this->configImporter()->getErrors(), array());
+
     // Check that all modules that were uninstalled are now reinstalled.
     $this->assertModules(array_keys($modules_to_uninstall), TRUE);
     foreach($modules_to_uninstall as $module => $info) {
diff --git a/core/modules/config/lib/Drupal/config/Tests/ConfigImportRecreateTest.php b/core/modules/config/lib/Drupal/config/Tests/ConfigImportRecreateTest.php
index 3f86c9b..ac77a58 100644
--- a/core/modules/config/lib/Drupal/config/Tests/ConfigImportRecreateTest.php
+++ b/core/modules/config/lib/Drupal/config/Tests/ConfigImportRecreateTest.php
@@ -59,7 +59,8 @@ public function setUp() {
       $this->container->get('lock'),
       $this->container->get('config.typed'),
       $this->container->get('module_handler'),
-      $this->container->get('theme_handler')
+      $this->container->get('theme_handler'),
+      $this->container->get('string_translation')
     );
   }
 
diff --git a/core/modules/config/lib/Drupal/config/Tests/ConfigImportUITest.php b/core/modules/config/lib/Drupal/config/Tests/ConfigImportUITest.php
index 084be15..94f35fb 100644
--- a/core/modules/config/lib/Drupal/config/Tests/ConfigImportUITest.php
+++ b/core/modules/config/lib/Drupal/config/Tests/ConfigImportUITest.php
@@ -7,6 +7,7 @@
 
 namespace Drupal\config\Tests;
 
+use Drupal\Component\Utility\String;
 use Drupal\Core\Config\InstallStorage;
 use Drupal\simpletest\WebTestBase;
 
@@ -312,4 +313,55 @@ function prepareSiteNameUpdate($new_site_name) {
     $config_data['name'] = $new_site_name;
     $staging->write('system.site', $config_data);
   }
+
+  /**
+   * Tests an import that results in an error.
+   */
+  function testImportErrorLog() {
+    $name_primary = 'config_test.dynamic.primary';
+    $name_secondary = 'config_test.dynamic.secondary';
+    $staging = $this->container->get('config.storage.staging');
+    $uuid = $this->container->get('uuid');
+
+    $values_primary = array(
+      'id' => 'primary',
+      'label' => 'Primary',
+      'weight' => 0,
+      'style' => NULL,
+      'test_dependencies' => array(),
+      'status' => TRUE,
+      'uuid' => $uuid->generate(),
+      'langcode' => 'en',
+      'dependencies' => array(),
+      'protected_property' => null,
+    );
+    $staging->write($name_primary, $values_primary);
+    $values_secondary = array(
+      'id' => 'secondary',
+      'label' => 'Secondary Sync',
+      'weight' => 0,
+      'style' => NULL,
+      'test_dependencies' => array(),
+      'status' => TRUE,
+      'uuid' => $uuid->generate(),
+      'langcode' => 'en',
+      // Add a dependency on primary, to ensure that is synced first.
+      'dependencies' => array(
+        'entity' => array($name_primary),
+      ),
+      'protected_property' => null,
+    );
+    $staging->write($name_secondary, $values_secondary);
+    // Verify that there are configuration differences to import.
+    $this->drupalGet('admin/config/development/configuration');
+    $this->assertNoText(t('There are no configuration changes.'));
+
+    // Attempt to import configuration and verify that an error message appears.
+    $this->drupalPostForm(NULL, array(), t('Import all'));
+    $this->assertText(String::format('Deleted and replaced configuration entity "@name"', array('@name' => $name_secondary)));
+    $this->assertText(t('The configuration was imported with errors.'));
+    $this->assertNoText(t('The configuration was imported successfully.'));
+    $this->assertText(t('There are no configuration changes.'));
+  }
+
 }
diff --git a/core/modules/config/lib/Drupal/config/Tests/ConfigImporterTest.php b/core/modules/config/lib/Drupal/config/Tests/ConfigImporterTest.php
index ff154b7..7597659 100644
--- a/core/modules/config/lib/Drupal/config/Tests/ConfigImporterTest.php
+++ b/core/modules/config/lib/Drupal/config/Tests/ConfigImporterTest.php
@@ -7,6 +7,7 @@
 
 namespace Drupal\config\Tests;
 
+use Drupal\Component\Utility\String;
 use Drupal\Core\Config\ConfigImporter;
 use Drupal\Core\Config\ConfigImporterException;
 use Drupal\Core\Config\StorageComparer;
@@ -64,7 +65,8 @@ function setUp() {
       $this->container->get('lock'),
       $this->container->get('config.typed'),
       $this->container->get('module_handler'),
-      $this->container->get('theme_handler')
+      $this->container->get('theme_handler'),
+      $this->container->get('string_translation')
     );
   }
 
@@ -149,6 +151,8 @@ function testDeleted() {
     $this->assertTrue(isset($GLOBALS['hook_config_test']['delete']));
 
     $this->assertFalse($this->configImporter->hasUnprocessedConfigurationChanges());
+    $logs = $this->configImporter->getErrors();
+    $this->assertEqual(count($logs), 0);
   }
 
   /**
@@ -196,6 +200,274 @@ function testNew() {
 
     // Verify that there is nothing more to import.
     $this->assertFalse($this->configImporter->hasUnprocessedConfigurationChanges());
+    $logs = $this->configImporter->getErrors();
+    $this->assertEqual(count($logs), 0);
+  }
+
+  /**
+   * Tests that secondary writes are overwritten.
+   */
+  function testSecondaryWritePrimaryFirst() {
+    $name_primary = 'config_test.dynamic.primary';
+    $name_secondary = 'config_test.dynamic.secondary';
+    $staging = $this->container->get('config.storage.staging');
+    $uuid = $this->container->get('uuid');
+
+    $values_primary = array(
+      'id' => 'primary',
+      'label' => 'Primary',
+      'weight' => 0,
+      'uuid' => $uuid->generate(),
+    );
+    $staging->write($name_primary, $values_primary);
+    $values_secondary = array(
+      'id' => 'secondary',
+      'label' => 'Secondary Sync',
+      'weight' => 0,
+      'uuid' => $uuid->generate(),
+      // Add a dependency on primary, to ensure that is synced first.
+      'dependencies' => array(
+        'entity' => array($name_primary),
+      )
+    );
+    $staging->write($name_secondary, $values_secondary);
+
+    // Import.
+    $this->configImporter->reset()->import();
+
+    $entity_storage = \Drupal::entityManager()->getStorage('config_test');
+    $primary = $entity_storage->load('primary');
+    $this->assertEqual($primary->id(), 'primary');
+    $this->assertEqual($primary->uuid(), $values_primary['uuid']);
+    $this->assertEqual($primary->label(), $values_primary['label']);
+    $secondary = $entity_storage->load('secondary');
+    $this->assertEqual($secondary->id(), 'secondary');
+    $this->assertEqual($secondary->uuid(), $values_secondary['uuid']);
+    $this->assertEqual($secondary->label(), $values_secondary['label']);
+
+    $logs = $this->configImporter->getErrors();
+    $this->assertEqual(count($logs), 1);
+    $this->assertEqual($logs[0], String::format('Deleted and replaced configuration entity "@name"', array('@name' => $name_secondary)));
+  }
+
+  /**
+   * Tests that secondary writes are overwritten.
+   */
+  function testSecondaryWriteSecondaryFirst() {
+    $name_primary = 'config_test.dynamic.primary';
+    $name_secondary = 'config_test.dynamic.secondary';
+    $staging = $this->container->get('config.storage.staging');
+    $uuid = $this->container->get('uuid');
+
+    $values_primary = array(
+      'id' => 'primary',
+      'label' => 'Primary',
+      'weight' => 0,
+      'uuid' => $uuid->generate(),
+      // Add a dependency on secondary, so that is synced first.
+      'dependencies' => array(
+        'entity' => array($name_secondary),
+      )
+    );
+    $staging->write($name_primary, $values_primary);
+    $values_secondary = array(
+      'id' => 'secondary',
+      'label' => 'Secondary Sync',
+      'weight' => 0,
+      'uuid' => $uuid->generate(),
+    );
+    $staging->write($name_secondary, $values_secondary);
+
+    // Import.
+    $this->configImporter->reset()->import();
+
+    $entity_storage = \Drupal::entityManager()->getStorage('config_test');
+    $primary = $entity_storage->load('primary');
+    $this->assertEqual($primary->id(), 'primary');
+    $this->assertEqual($primary->uuid(), $values_primary['uuid']);
+    $this->assertEqual($primary->label(), $values_primary['label']);
+    $secondary = $entity_storage->load('secondary');
+    $this->assertEqual($secondary->id(), 'secondary');
+    $this->assertEqual($secondary->uuid(), $values_secondary['uuid']);
+    $this->assertEqual($secondary->label(), $values_secondary['label']);
+
+    $logs = $this->configImporter->getErrors();
+    $this->assertEqual(count($logs), 1);
+    $message = String::format('config_test entity with ID @name already exists', array('@name' => 'secondary'));
+    $this->assertEqual($logs[0], String::format('Unexpected error during import with operation @op for @name: @message.', array('@op' => 'create', '@name' => $name_primary, '@message' => $message)));
+  }
+
+  /**
+   * Tests that secondary updates for deleted files work as expected.
+   */
+  function testSecondaryUpdateDeletedDeleterFirst() {
+    $name_deleter = 'config_test.dynamic.deleter';
+    $name_deletee = 'config_test.dynamic.deletee';
+    $name_other = 'config_test.dynamic.other';
+    $storage = $this->container->get('config.storage');
+    $staging = $this->container->get('config.storage.staging');
+    $uuid = $this->container->get('uuid');
+
+    $values_deleter = array(
+      'id' => 'deleter',
+      'label' => 'Deleter',
+      'weight' => 0,
+      'uuid' => $uuid->generate(),
+    );
+    $storage->write($name_deleter, $values_deleter);
+    $values_deleter['label'] = 'Updated Deleter';
+    $staging->write($name_deleter, $values_deleter);
+    $values_deletee = array(
+      'id' => 'deletee',
+      'label' => 'Deletee',
+      'weight' => 0,
+      'uuid' => $uuid->generate(),
+      // Add a dependency on deleter, to make sure that is synced first.
+      'dependencies' => array(
+        'entity' => array($name_deleter),
+      )
+    );
+    $storage->write($name_deletee, $values_deletee);
+    $values_deletee['label'] = 'Updated Deletee';
+    $staging->write($name_deletee, $values_deletee);
+
+    // Ensure that import will continue after the error.
+    $values_other = array(
+      'id' => 'other',
+      'label' => 'Other',
+      'weight' => 0,
+      'uuid' => $uuid->generate(),
+      // Add a dependency on deleter, to make sure that is synced first. This
+      // will also be synced after the deletee due to alphabetical ordering.
+      'dependencies' => array(
+        'entity' => array($name_deleter),
+      )
+    );
+    $storage->write($name_other, $values_other);
+    $values_other['label'] = 'Updated other';
+    $staging->write($name_other, $values_other);
+
+    // Check update changelist order.
+    $updates = $this->configImporter->reset()->getStorageComparer()->getChangelist('update');
+    $expected = array(
+      $name_deleter,
+      $name_deletee,
+      $name_other,
+    );
+    $this->assertIdentical($expected, $updates);
+
+    // Import.
+    $this->configImporter->import();
+
+    $entity_storage = \Drupal::entityManager()->getStorage('config_test');
+    $deleter = $entity_storage->load('deleter');
+    $this->assertEqual($deleter->id(), 'deleter');
+    $this->assertEqual($deleter->uuid(), $values_deleter['uuid']);
+    $this->assertEqual($deleter->label(), $values_deleter['label']);
+
+    // The deletee was deleted in
+    // \Drupal\config_test\Entity\ConfigTest::postSave().
+    $this->assertFalse($entity_storage->load('deletee'));
+
+    $other = $entity_storage->load('other');
+    $this->assertEqual($other->id(), 'other');
+    $this->assertEqual($other->uuid(), $values_other['uuid']);
+    $this->assertEqual($other->label(), $values_other['label']);
+
+    $logs = $this->configImporter->getErrors();
+    $this->assertEqual(count($logs), 1);
+    $this->assertEqual($logs[0], String::format('Update target "@name" is missing.', array('@name' => $name_deletee)));
+  }
+
+  /**
+   * Tests that secondary updates for deleted files work as expected.
+   */
+  function testSecondaryUpdateDeletedDeleteeFirst() {
+    $name_deleter = 'config_test.dynamic.deleter';
+    $name_deletee = 'config_test.dynamic.deletee';
+    $storage = $this->container->get('config.storage');
+    $staging = $this->container->get('config.storage.staging');
+    $uuid = $this->container->get('uuid');
+
+    $values_deleter = array(
+      'id' => 'deleter',
+      'label' => 'Deleter',
+      'weight' => 0,
+      'uuid' => $uuid->generate(),
+      // Add a dependency on deletee, to make sure that is synced first.
+      'dependencies' => array(
+        'entity' => array($name_deletee),
+      ),
+    );
+    $storage->write($name_deleter, $values_deleter);
+    $values_deleter['label'] = 'Updated Deleter';
+    $staging->write($name_deleter, $values_deleter);
+    $values_deletee = array(
+      'id' => 'deletee',
+      'label' => 'Deletee',
+      'weight' => 0,
+      'uuid' => $uuid->generate(),
+    );
+    $storage->write($name_deletee, $values_deletee);
+    $values_deletee['label'] = 'Updated Deletee';
+    $staging->write($name_deletee, $values_deletee);
+
+    // Import.
+    $this->configImporter->reset()->import();
+
+    $entity_storage = \Drupal::entityManager()->getStorage('config_test');
+    $deleter = $entity_storage->load('deleter');
+    $this->assertEqual($deleter->id(), 'deleter');
+    $this->assertEqual($deleter->uuid(), $values_deleter['uuid']);
+    $this->assertEqual($deleter->label(), $values_deleter['label']);
+    // @todo The deletee entity does not exist as the update worked but the
+    //   entity was deleted after that. There is also no log message as this
+    //   happened outside of the config importer.
+    $this->assertFalse($entity_storage->load('deletee'));
+    $logs = $this->configImporter->getErrors();
+    $this->assertEqual(count($logs), 0);
+  }
+
+  /**
+   * Tests that secondary deletes for deleted files work as expected.
+   */
+  function testSecondaryDeletedDeleteeSecond() {
+    $name_deleter = 'config_test.dynamic.deleter';
+    $name_deletee = 'config_test.dynamic.deletee';
+    $storage = $this->container->get('config.storage');
+
+    $uuid = $this->container->get('uuid');
+
+    $values_deleter = array(
+      'id' => 'deleter',
+      'label' => 'Deleter',
+      'weight' => 0,
+      'uuid' => $uuid->generate(),
+      // Add a dependency on deletee, to make sure this delete is synced first.
+      'dependencies' => array(
+        'entity' => array($name_deletee),
+      ),
+    );
+    $storage->write($name_deleter, $values_deleter);
+    $values_deletee = array(
+      'id' => 'deletee',
+      'label' => 'Deletee',
+      'weight' => 0,
+      'uuid' => $uuid->generate(),
+    );
+    $storage->write($name_deletee, $values_deletee);
+
+    // Import.
+    $this->configImporter->reset()->import();
+
+    $entity_storage = \Drupal::entityManager()->getStorage('config_test');
+    $this->assertFalse($entity_storage->load('deleter'));
+    $this->assertFalse($entity_storage->load('deletee'));
+    // The deletee entity does not exist as the delete worked and although the
+    // delete occurred in \Drupal\config_test\Entity\ConfigTest::postDelete()
+    // this does not matter.
+    $logs = $this->configImporter->getErrors();
+    $this->assertEqual(count($logs), 0);
   }
 
   /**
@@ -251,6 +523,8 @@ function testUpdated() {
 
     // Verify that there is nothing more to import.
     $this->assertFalse($this->configImporter->hasUnprocessedConfigurationChanges());
+    $logs = $this->configImporter->getErrors();
+    $this->assertEqual(count($logs), 0);
   }
 }
 
diff --git a/core/modules/config/tests/config_test/lib/Drupal/config_test/Entity/ConfigTest.php b/core/modules/config/tests/config_test/lib/Drupal/config_test/Entity/ConfigTest.php
index d5217bf..1f44f4f 100644
--- a/core/modules/config/tests/config_test/lib/Drupal/config_test/Entity/ConfigTest.php
+++ b/core/modules/config/tests/config_test/lib/Drupal/config_test/Entity/ConfigTest.php
@@ -10,6 +10,7 @@
 use Drupal\Core\Config\Entity\ConfigEntityBase;
 use Drupal\config_test\ConfigTestInterface;
 use Drupal\Core\Config\Entity\ConfigEntityInterface;
+use Drupal\Core\Entity\EntityStorageInterface;
 
 /**
  * Defines the ConfigTest configuration entity.
@@ -109,6 +110,37 @@ public static function sort(ConfigEntityInterface $a, ConfigEntityInterface $b)
   /**
    * {@inheritdoc}
    */
+  public function postSave(EntityStorageInterface $storage, $update = TRUE) {
+    // Used to test secondary writes during config sync.
+    if ($this->id() == 'primary') {
+      $secondary = $storage->create(array(
+        'id' => 'secondary',
+        'label' => 'Secondary Default',
+      ));
+      $secondary->save();
+    }
+    if ($this->id() == 'deleter') {
+      $deletee = $storage->load('deletee');
+      $deletee->delete();
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function postDelete(EntityStorageInterface $storage, array $entities) {
+    parent::postDelete($storage, $entities);
+    foreach ($entities as $entity) {
+      if ($entity->id() == 'deleter') {
+        $deletee = $storage->load('deletee');
+        $deletee->delete();
+      }
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
   public function calculateDependencies() {
     parent::calculateDependencies();
     foreach ($this->test_dependencies as $type => $deps) {
diff --git a/core/modules/entity_reference/entity_reference.module b/core/modules/entity_reference/entity_reference.module
index cce3e3f..846a723 100644
--- a/core/modules/entity_reference/entity_reference.module
+++ b/core/modules/entity_reference/entity_reference.module
@@ -72,6 +72,11 @@ function entity_reference_field_config_update(FieldConfigInterface $field) {
     return;
   }
 
+  if ($field->isSyncing()) {
+    // Don't change anything during a configuration sync.
+    return;
+  }
+
   if ($field->getSetting('target_type') == $field->original->getSetting('target_type')) {
     // Target type didn't change.
     return;
diff --git a/core/modules/field/lib/Drupal/field/Tests/FieldImportDeleteTest.php b/core/modules/field/lib/Drupal/field/Tests/FieldImportDeleteTest.php
index d2388f7..b0485c4 100644
--- a/core/modules/field/lib/Drupal/field/Tests/FieldImportDeleteTest.php
+++ b/core/modules/field/lib/Drupal/field/Tests/FieldImportDeleteTest.php
@@ -7,6 +7,8 @@
 
 namespace Drupal\field\Tests;
 
+use Drupal\Component\Utility\String;
+
 /**
  * Tests deleting fields and instances as part of config import.
  */
@@ -31,13 +33,21 @@ public static function getInfo() {
    * Tests deleting fields and instances as part of config import.
    */
   public function testImportDelete() {
+    // At this point there are 5 field configuration objects in the active
+    // storage.
+    // - field.field.entity_test.field_test_import
+    // - field.field.entity_test.field_test_import_2
+    // - field.instance.entity_test.entity_test.field_test_import
+    // - field.instance.entity_test.entity_test.field_test_import_2
+    // - field.instance.entity_test.test_bundle.field_test_import_2
+
     $field_name = 'field_test_import';
     $field_id = "entity_test.$field_name";
     $field_name_2 = 'field_test_import_2';
     $field_id_2 = "entity_test.$field_name_2";
-    $instance_id = "entity_test.test_bundle.$field_name";
-    $instance_id_2a = "entity_test.test_bundle.$field_name_2";
-    $instance_id_2b = "entity_test.test_bundle_2.$field_name_2";
+    $instance_id = "entity_test.entity_test.$field_name";
+    $instance_id_2a = "entity_test.entity_test.$field_name_2";
+    $instance_id_2b = "entity_test.test_bundle.$field_name_2";
     $field_config_name = "field.field.$field_id";
     $field_config_name_2 = "field.field.$field_id_2";
     $instance_config_name = "field.instance.$instance_id";
@@ -45,7 +55,7 @@ public function testImportDelete() {
     $instance_config_name_2b = "field.instance.$instance_id_2b";
 
     // Create a second bundle for the 'Entity test' entity type.
-    entity_test_create_bundle('test_bundle_2');
+    entity_test_create_bundle('test_bundle');
 
     // Import default config.
     $this->installConfig(array('field_test_config'));
@@ -57,11 +67,14 @@ public function testImportDelete() {
     $active = $this->container->get('config.storage');
     $staging = $this->container->get('config.storage.staging');
     $this->copyConfig($active, $staging);
-    $staging->delete($field_config_name);
-    $staging->delete($field_config_name_2);
-    $staging->delete($instance_config_name);
-    $staging->delete($instance_config_name_2a);
-    $staging->delete($instance_config_name_2b);
+    $this->assertTrue($staging->delete($field_config_name), String::format('Deleted field: !field', array('!field' => $field_config_name)));
+    $this->assertTrue($staging->delete($field_config_name_2), String::format('Deleted field: !field', array('!field' => $field_config_name_2)));
+    $this->assertTrue($staging->delete($instance_config_name), String::format('Deleted field instance: !field_instance', array('!field_instance' => $instance_config_name)));
+    $this->assertTrue($staging->delete($instance_config_name_2a), String::format('Deleted field instance: !field_instance', array('!field_instance' => $instance_config_name_2a)));
+    $this->assertTrue($staging->delete($instance_config_name_2b), String::format('Deleted field instance: !field_instance', array('!field_instance' => $instance_config_name_2b)));
+
+    $deletes = $this->configImporter()->getUnprocessedConfiguration('delete');
+    $this->assertEqual(count($deletes), 5, 'Importing configuration will delete 3 field instances and 2 fields.');
 
     // Import the content of the staging directory.
     $this->configImporter()->import();
diff --git a/core/modules/filter/lib/Drupal/filter/Entity/FilterFormat.php b/core/modules/filter/lib/Drupal/filter/Entity/FilterFormat.php
index 365a8aa..2c475a5 100644
--- a/core/modules/filter/lib/Drupal/filter/Entity/FilterFormat.php
+++ b/core/modules/filter/lib/Drupal/filter/Entity/FilterFormat.php
@@ -239,7 +239,7 @@ public function postSave(EntityStorageInterface $storage, $update = TRUE) {
       // Clear the filter cache whenever a text format is updated.
       Cache::deleteTags(array('filter_format' => $this->id()));
     }
-    else {
+    elseif (!$this->isSyncing()) {
       // Default configuration of modules and installation profiles is allowed
       // to specify a list of user roles to grant access to for the new format;
       // apply the defined user role permissions when a new format is inserted
diff --git a/core/modules/image/image.module b/core/modules/image/image.module
index dc25998..61b30b9 100644
--- a/core/modules/image/image.module
+++ b/core/modules/image/image.module
@@ -387,6 +387,10 @@ function image_entity_presave(EntityInterface $entity) {
     return;
   }
 
+  if ($field->isSyncing()) {
+    return;
+  }
+
   $fid = $entity->settings['default_image']['fid'];
   if ($fid) {
     $original_fid = isset($entity->original) ? $entity->original->settings['default_image']['fid'] : NULL;
diff --git a/core/modules/image/lib/Drupal/image/Entity/ImageStyle.php b/core/modules/image/lib/Drupal/image/Entity/ImageStyle.php
index 7bd7537..6ac64a6 100644
--- a/core/modules/image/lib/Drupal/image/Entity/ImageStyle.php
+++ b/core/modules/image/lib/Drupal/image/Entity/ImageStyle.php
@@ -105,7 +105,9 @@ public function postSave(EntityStorageInterface $storage, $update = TRUE) {
         // The old image style name needs flushing after a rename.
         $this->original->flush();
         // Update field instance settings if necessary.
-        static::replaceImageStyle($this);
+        if (!$this->isSyncing()) {
+          static::replaceImageStyle($this);
+        }
       }
       else {
         // Flush image style when updating without changing the name.
@@ -126,7 +128,7 @@ public static function postDelete(EntityStorageInterface $storage, array $entiti
       // Check whether field instance settings need to be updated.
       // In case no replacement style was specified, all image fields that are
       // using the deleted style are left in a broken state.
-      if ($new_id = $style->getReplacementID()) {
+      if (!$style->isSyncing() && $new_id = $style->getReplacementID()) {
         // The deleted ID is still set as originalID.
         $style->setName($new_id);
         static::replaceImageStyle($style);
diff --git a/core/modules/menu/menu.module b/core/modules/menu/menu.module
index 76da041..47b5813 100644
--- a/core/modules/menu/menu.module
+++ b/core/modules/menu/menu.module
@@ -133,6 +133,11 @@ function menu_menu_insert(Menu $menu) {
   if (\Drupal::moduleHandler()->moduleExists('block')) {
     \Drupal::service('plugin.manager.block')->clearCachedDefinitions();
   }
+
+  if ($menu->isSyncing()) {
+    return;
+  }
+
   // Make sure the menu is present in the active menus variable so that its
   // items may appear in the menu active trail.
   // See menu_set_active_menu_names().
@@ -322,6 +327,9 @@ function menu_node_update(EntityInterface $node) {
  * Implements hook_node_type_insert().
  */
 function menu_node_type_insert(NodeTypeInterface $type) {
+  if ($type->isSyncing()) {
+    return;
+  }
   \Drupal::config('menu.entity.node.' . $type->id())
     ->set('available_menus', array('main'))
     ->set('parent', 'main:0')
@@ -332,6 +340,9 @@ function menu_node_type_insert(NodeTypeInterface $type) {
  * Implements hook_node_type_delete().
  */
 function menu_node_type_delete(NodeTypeInterface $type) {
+  if ($type->isSyncing()) {
+    return;
+  }
   \Drupal::config('menu.entity.node.' . $type->id())->delete();
 }
 
diff --git a/core/modules/simpletest/lib/Drupal/simpletest/TestBase.php b/core/modules/simpletest/lib/Drupal/simpletest/TestBase.php
index 50f2eb1..4005305 100644
--- a/core/modules/simpletest/lib/Drupal/simpletest/TestBase.php
+++ b/core/modules/simpletest/lib/Drupal/simpletest/TestBase.php
@@ -1527,7 +1527,8 @@ public function configImporter() {
         $this->container->get('lock'),
         $this->container->get('config.typed'),
         $this->container->get('module_handler'),
-        $this->container->get('theme_handler')
+        $this->container->get('theme_handler'),
+        $this->container->get('string_translation')
       );
     }
     // Always recalculate the changelist when called.
diff --git a/core/modules/taxonomy/lib/Drupal/taxonomy/Entity/Vocabulary.php b/core/modules/taxonomy/lib/Drupal/taxonomy/Entity/Vocabulary.php
index f5a7ba7..ec46b6b 100644
--- a/core/modules/taxonomy/lib/Drupal/taxonomy/Entity/Vocabulary.php
+++ b/core/modules/taxonomy/lib/Drupal/taxonomy/Entity/Vocabulary.php
@@ -102,7 +102,7 @@ public function postSave(EntityStorageInterface $storage, $update = TRUE) {
     if (!$update) {
       entity_invoke_bundle_hook('create', 'taxonomy_term', $this->id());
     }
-    elseif ($this->getOriginalId() != $this->id()) {
+    elseif ($this->getOriginalId() != $this->id() && !$this->isSyncing()) {
       // Reflect machine name changes in the definitions of existing 'taxonomy'
       // fields.
       $field_ids = array();
@@ -153,6 +153,13 @@ public static function preDelete(EntityStorageInterface $storage, array $entitie
   public static function postDelete(EntityStorageInterface $storage, array $entities) {
     parent::postDelete($storage, $entities);
 
+    // Reset caches.
+    $storage->resetCache(array_keys($entities));
+
+    if (reset($entities)->isSyncing()) {
+      return;
+    }
+
     $vocabularies = array();
     foreach ($entities as $vocabulary) {
       $vocabularies[$vocabulary->id()] = $vocabulary->id();