diff --git a/core/modules/content_translation/content_translation.module b/core/modules/content_translation/content_translation.module
index 9ce46580ce9313ab014d8092874b8f90d338221d..1b09b39310eeaee568418ac07d451320fdbbe96f 100644
--- a/core/modules/content_translation/content_translation.module
+++ b/core/modules/content_translation/content_translation.module
@@ -163,6 +163,8 @@ function content_translation_entity_type_alter(array &$entity_types) {
       }
       $entity_type->set('translation', $translation);
     }
+
+    $entity_type->addConstraint('ContentTranslationSynchronizedFields');
   }
 }
 
diff --git a/core/modules/content_translation/content_translation.services.yml b/core/modules/content_translation/content_translation.services.yml
index f7cc11fff2b173f8fcb21e39b5aff658cd00932d..066142fac3fd1ebd93645806b21b7b6a82dd7b3a 100644
--- a/core/modules/content_translation/content_translation.services.yml
+++ b/core/modules/content_translation/content_translation.services.yml
@@ -1,7 +1,7 @@
 services:
   content_translation.synchronizer:
     class: Drupal\content_translation\FieldTranslationSynchronizer
-    arguments: ['@entity.manager']
+    arguments: ['@entity.manager', '@plugin.manager.field.field_type']
 
   content_translation.subscriber:
     class: Drupal\content_translation\Routing\ContentTranslationRouteSubscriber
diff --git a/core/modules/content_translation/src/FieldTranslationSynchronizer.php b/core/modules/content_translation/src/FieldTranslationSynchronizer.php
index 13b805df8ac2c8c097381647b10b39b85718252a..3f3595ecbda0787a59e6e8c49509e10960ee8855 100644
--- a/core/modules/content_translation/src/FieldTranslationSynchronizer.php
+++ b/core/modules/content_translation/src/FieldTranslationSynchronizer.php
@@ -5,6 +5,8 @@
 use Drupal\Core\Config\Entity\ThirdPartySettingsInterface;
 use Drupal\Core\Entity\ContentEntityInterface;
 use Drupal\Core\Entity\EntityManagerInterface;
+use Drupal\Core\Field\FieldDefinitionInterface;
+use Drupal\Core\Field\FieldTypePluginManagerInterface;
 
 /**
  * Provides field translation synchronization capabilities.
@@ -18,14 +20,57 @@ class FieldTranslationSynchronizer implements FieldTranslationSynchronizerInterf
    */
   protected $entityManager;
 
+  /**
+   * The field type plugin manager.
+   *
+   * @var \Drupal\Core\Field\FieldTypePluginManagerInterface
+   */
+  protected $fieldTypeManager;
+
   /**
    * Constructs a FieldTranslationSynchronizer object.
    *
    * @param \Drupal\Core\Entity\EntityManagerInterface $entityManager
    *   The entity manager.
+   * @param \Drupal\Core\Field\FieldTypePluginManagerInterface $field_type_manager
+   *   The field type plugin manager.
    */
-  public function __construct(EntityManagerInterface $entityManager) {
+  public function __construct(EntityManagerInterface $entityManager, FieldTypePluginManagerInterface $field_type_manager) {
     $this->entityManager = $entityManager;
+    $this->fieldTypeManager = $field_type_manager;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getFieldSynchronizedProperties(FieldDefinitionInterface $field_definition) {
+    $properties = [];
+    $settings = $this->getFieldSynchronizationSettings($field_definition);
+    foreach ($settings as $group => $translatable) {
+      if (!$translatable) {
+        $field_type_definition = $this->fieldTypeManager->getDefinition($field_definition->getType());
+        if (!empty($field_type_definition['column_groups'][$group]['columns'])) {
+          $properties = array_merge($properties, $field_type_definition['column_groups'][$group]['columns']);
+        }
+      }
+    }
+    return $properties;
+  }
+
+  /**
+   * Returns the synchronization settings for the specified field.
+   *
+   * @param \Drupal\Core\Field\FieldDefinitionInterface $field_definition
+   *   A field definition.
+   *
+   * @return string[]
+   *   An array of synchronized field property names.
+   */
+  protected function getFieldSynchronizationSettings(FieldDefinitionInterface $field_definition) {
+    if ($field_definition instanceof ThirdPartySettingsInterface && $field_definition->isTranslatable()) {
+      return $field_definition->getThirdPartySetting('content_translation', 'translation_sync', []);
+    }
+    return [];
   }
 
   /**
@@ -33,7 +78,6 @@ public function __construct(EntityManagerInterface $entityManager) {
    */
   public function synchronizeFields(ContentEntityInterface $entity, $sync_langcode, $original_langcode = NULL) {
     $translations = $entity->getTranslationLanguages();
-    $field_type_manager = \Drupal::service('plugin.manager.field.field_type');
 
     // If we have no information about what to sync to, if we are creating a new
     // entity, if we have no translations for the current entity and we are not
@@ -43,21 +87,55 @@ public function synchronizeFields(ContentEntityInterface $entity, $sync_langcode
     }
 
     // If the entity language is being changed there is nothing to synchronize.
-    $entity_type = $entity->getEntityTypeId();
-    $entity_unchanged = isset($entity->original) ? $entity->original : $this->entityManager->getStorage($entity_type)->loadUnchanged($entity->id());
+    $entity_unchanged = $this->getOriginalEntity($entity);
     if ($entity->getUntranslated()->language()->getId() != $entity_unchanged->getUntranslated()->language()->getId()) {
       return;
     }
 
+    if ($entity->isNewRevision()) {
+      if ($entity->isDefaultTranslationAffectedOnly()) {
+        // If changes to untranslatable fields are configured to affect only the
+        // default translation, we need to skip synchronization in pending
+        // revisions, otherwise multiple translations would be affected.
+        if (!$entity->isDefaultRevision()) {
+          return;
+        }
+        // When this mode is enabled, changes to synchronized properties are
+        // allowed only in the default translation, thus we need to make sure this
+        // is always used as source for the synchronization process.
+        else {
+          $sync_langcode = $entity->getUntranslated()->language()->getId();
+        }
+      }
+      elseif ($entity->isDefaultRevision()) {
+        // If a new default revision is being saved, but a newer default
+        // revision was created meanwhile, use any other translation as source
+        // for synchronization, since that will have been merged from the
+        // default revision. In this case the actual language does not matter as
+        // synchronized properties are the same for all the translations in the
+        // default revision.
+        /** @var \Drupal\Core\Entity\ContentEntityInterface $default_revision */
+        $default_revision = $this->entityManager
+          ->getStorage($entity->getEntityTypeId())
+          ->load($entity->id());
+        if ($default_revision->getLoadedRevisionId() !== $entity->getLoadedRevisionId()) {
+          $other_langcodes = array_diff_key($default_revision->getTranslationLanguages(), [$sync_langcode => FALSE]);
+          if ($other_langcodes) {
+            $sync_langcode = key($other_langcodes);
+          }
+        }
+      }
+    }
+
     /** @var \Drupal\Core\Field\FieldItemListInterface $items */
     foreach ($entity as $field_name => $items) {
       $field_definition = $items->getFieldDefinition();
-      $field_type_definition = $field_type_manager->getDefinition($field_definition->getType());
+      $field_type_definition = $this->fieldTypeManager->getDefinition($field_definition->getType());
       $column_groups = $field_type_definition['column_groups'];
 
       // Sync if the field is translatable, not empty, and the synchronization
       // setting is enabled.
-      if ($field_definition instanceof ThirdPartySettingsInterface && $field_definition->isTranslatable() && !$items->isEmpty() && $translation_sync = $field_definition->getThirdPartySetting('content_translation', 'translation_sync')) {
+      if (($translation_sync = $this->getFieldSynchronizationSettings($field_definition)) && !$items->isEmpty()) {
         // Retrieve all the untranslatable column groups and merge them into
         // single list.
         $groups = array_keys(array_diff($translation_sync, array_filter($translation_sync)));
@@ -101,6 +179,26 @@ public function synchronizeFields(ContentEntityInterface $entity, $sync_langcode
     }
   }
 
+  /**
+   * Returns the original unchanged entity to be used to detect changes.
+   *
+   * @param \Drupal\Core\Entity\ContentEntityInterface $entity
+   *   The entity being changed.
+   *
+   * @return \Drupal\Core\Entity\ContentEntityInterface
+   *   The unchanged entity.
+   */
+  protected function getOriginalEntity(ContentEntityInterface $entity) {
+    if (!isset($entity->original)) {
+      $storage = $this->entityManager->getStorage($entity->getEntityTypeId());
+      $original = $entity->isDefaultRevision() ? $storage->loadUnchanged($entity->id()) : $storage->loadRevision($entity->getLoadedRevisionId());
+    }
+    else {
+      $original = $entity->original;
+    }
+    return $original;
+  }
+
   /**
    * {@inheritdoc}
    */
@@ -174,9 +272,7 @@ public function synchronizeItems(array &$values, array $unchanged_items, $sync_l
           // items and the other columns from the existing values. This only
           // works if the delta exists in the language.
           elseif ($created && !empty($original_field_values[$langcode][$delta])) {
-            $item_columns_to_sync = array_intersect_key($source_items[$delta], array_flip($columns));
-            $item_columns_to_keep = array_diff_key($original_field_values[$langcode][$delta], array_flip($columns));
-            $values[$langcode][$delta] = $item_columns_to_sync + $item_columns_to_keep;
+            $values[$langcode][$delta] = $this->createMergedItem($source_items[$delta], $original_field_values[$langcode][$delta], $columns);
           }
           // If the delta doesn't exist, copy from the source language.
           elseif ($created) {
@@ -190,13 +286,37 @@ public function synchronizeItems(array &$values, array $unchanged_items, $sync_l
             // If the value has only been reordered we just move the old one in
             // the new position.
             $item = isset($original_field_values[$langcode][$old_delta]) ? $original_field_values[$langcode][$old_delta] : $source_items[$new_delta];
-            $values[$langcode][$new_delta] = $item;
+            // When saving a default revision starting from a pending revision,
+            // we may have desynchronized field values, so we make sure that
+            // untranslatable properties are synchronized, even if in any other
+            // situation this would not be necessary.
+            $values[$langcode][$new_delta] = $this->createMergedItem($source_items[$new_delta], $item, $columns);
           }
         }
       }
     }
   }
 
+  /**
+   * Creates a merged item.
+   *
+   * @param array $source_item
+   *   An item containing the untranslatable properties to be synchronized.
+   * @param array $target_item
+   *   An item containing the translatable properties to be kept.
+   * @param string[] $properties
+   *   An array of properties to be synchronized.
+   *
+   * @return array
+   *   A merged item array.
+   */
+  protected function createMergedItem(array $source_item, array $target_item, array $properties) {
+    $property_keys = array_flip($properties);
+    $item_properties_to_sync = array_intersect_key($source_item, $property_keys);
+    $item_properties_to_keep = array_diff_key($target_item, $property_keys);
+    return $item_properties_to_sync + $item_properties_to_keep;
+  }
+
   /**
    * Computes a hash code for the specified item.
    *
diff --git a/core/modules/content_translation/src/FieldTranslationSynchronizerInterface.php b/core/modules/content_translation/src/FieldTranslationSynchronizerInterface.php
index 88cb9217cdb1bdf97bd41a55586db520e7dfca39..a07ac59f8ccb09f7e74ab993db6483cfdf0cb30f 100644
--- a/core/modules/content_translation/src/FieldTranslationSynchronizerInterface.php
+++ b/core/modules/content_translation/src/FieldTranslationSynchronizerInterface.php
@@ -3,6 +3,7 @@
 namespace Drupal\content_translation;
 
 use Drupal\Core\Entity\ContentEntityInterface;
+use Drupal\Core\Field\FieldDefinitionInterface;
 
 /**
  * Provides field translation synchronization capabilities.
@@ -54,4 +55,15 @@ public function synchronizeFields(ContentEntityInterface $entity, $sync_langcode
    */
   public function synchronizeItems(array &$field_values, array $unchanged_items, $sync_langcode, array $translations, array $columns);
 
+  /**
+   * Returns the synchronized properties for the specified field definition.
+   *
+   * @param \Drupal\Core\Field\FieldDefinitionInterface $field_definition
+   *   A field definition.
+   *
+   * @return string[]
+   *   An array of synchronized field property names.
+   */
+  public function getFieldSynchronizedProperties(FieldDefinitionInterface $field_definition);
+
 }
diff --git a/core/modules/content_translation/src/Plugin/Validation/Constraint/ContentTranslationSynchronizedFieldsConstraint.php b/core/modules/content_translation/src/Plugin/Validation/Constraint/ContentTranslationSynchronizedFieldsConstraint.php
new file mode 100644
index 0000000000000000000000000000000000000000..0d2bc52878912487331af461f6d09fa98b4cc5ba
--- /dev/null
+++ b/core/modules/content_translation/src/Plugin/Validation/Constraint/ContentTranslationSynchronizedFieldsConstraint.php
@@ -0,0 +1,25 @@
+<?php
+
+namespace Drupal\content_translation\Plugin\Validation\Constraint;
+
+use Symfony\Component\Validator\Constraint;
+
+/**
+ * Validation constraint for the entity changed timestamp.
+ *
+ * @internal
+ *
+ * @Constraint(
+ *   id = "ContentTranslationSynchronizedFields",
+ *   label = @Translation("Content translation synchronized fields", context = "Validation"),
+ *   type = {"entity"}
+ * )
+ */
+class ContentTranslationSynchronizedFieldsConstraint extends Constraint {
+
+  // In this case "elements" refers to "field properties", in fact it is what we
+  // are using in the UI elsewhere.
+  public $defaultRevisionMessage = 'Non-translatable field elements can only be changed when updating the current revision.';
+  public $defaultTranslationMessage = 'Non-translatable field elements can only be changed when updating the original language.';
+
+}
diff --git a/core/modules/content_translation/src/Plugin/Validation/Constraint/ContentTranslationSynchronizedFieldsConstraintValidator.php b/core/modules/content_translation/src/Plugin/Validation/Constraint/ContentTranslationSynchronizedFieldsConstraintValidator.php
new file mode 100644
index 0000000000000000000000000000000000000000..0a508c9e0e38c922d110b5a4665a0dc91c4ce8b5
--- /dev/null
+++ b/core/modules/content_translation/src/Plugin/Validation/Constraint/ContentTranslationSynchronizedFieldsConstraintValidator.php
@@ -0,0 +1,226 @@
+<?php
+
+namespace Drupal\content_translation\Plugin\Validation\Constraint;
+
+use Drupal\content_translation\ContentTranslationManagerInterface;
+use Drupal\content_translation\FieldTranslationSynchronizerInterface;
+use Drupal\Core\DependencyInjection\ContainerInjectionInterface;
+use Drupal\Core\Entity\ContentEntityInterface;
+use Drupal\Core\Entity\EntityTypeManagerInterface;
+use Drupal\Core\Field\FieldDefinitionInterface;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+use Symfony\Component\Validator\Constraint;
+use Symfony\Component\Validator\ConstraintValidator;
+
+/**
+ * Checks that synchronized fields are handled correctly in pending revisions.
+ *
+ * As for untranslatable fields, two modes are supported:
+ * - When changes to untranslatable fields are configured to affect all revision
+ *   translations, synchronized field properties can be changed only in default
+ *   revisions.
+ * - When changes to untranslatable fields affect are configured to affect only
+ *   the revision's default translation, synchronized field properties can be
+ *   changed only when editing the default translation. This may lead to
+ *   temporarily desynchronized values, when saving a pending revision for the
+ *   default translation that changes a synchronized property. These are
+ *   actually synchronized when saving changes to the default translation as a
+ *   new default revision.
+ *
+ * @see \Drupal\content_translation\Plugin\Validation\Constraint\ContentTranslationSynchronizedFieldsConstraint
+ * @see \Drupal\Core\Entity\Plugin\Validation\Constraint\EntityUntranslatableFieldsConstraintValidator
+ *
+ * @internal
+ */
+class ContentTranslationSynchronizedFieldsConstraintValidator extends ConstraintValidator implements ContainerInjectionInterface {
+
+  /**
+   * The entity type manager.
+   *
+   * @var \Drupal\Core\Entity\EntityTypeManagerInterface
+   */
+  protected $entityTypeManager;
+
+  /**
+   * The content translation manager.
+   *
+   * @var \Drupal\content_translation\ContentTranslationManagerInterface
+   */
+  protected $contentTranslationManager;
+
+  /**
+   * The field translation synchronizer.
+   *
+   * @var \Drupal\content_translation\FieldTranslationSynchronizerInterface
+   */
+  protected $synchronizer;
+
+  /**
+   * ContentTranslationSynchronizedFieldsConstraintValidator constructor.
+   *
+   * @param \Drupal\Core\Entity\EntityTypeManagerInterface $entity_type_manager
+   *   The entity type manager.
+   * @param \Drupal\content_translation\ContentTranslationManagerInterface $content_translation_manager
+   *   The content translation manager.
+   * @param \Drupal\content_translation\FieldTranslationSynchronizerInterface $synchronizer
+   *   The field translation synchronizer.
+   */
+  public function __construct(EntityTypeManagerInterface $entity_type_manager, ContentTranslationManagerInterface $content_translation_manager, FieldTranslationSynchronizerInterface $synchronizer) {
+    $this->entityTypeManager = $entity_type_manager;
+    $this->contentTranslationManager = $content_translation_manager;
+    $this->synchronizer = $synchronizer;
+  }
+
+  /**
+   * [@inheritdoc}
+   */
+  public static function create(ContainerInterface $container) {
+    return new static(
+      $container->get('entity_type.manager'),
+      $container->get('content_translation.manager'),
+      $container->get('content_translation.synchronizer')
+    );
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function validate($value, Constraint $constraint) {
+    /** @var \Drupal\content_translation\Plugin\Validation\Constraint\ContentTranslationSynchronizedFieldsConstraint $constraint */
+    /** @var \Drupal\Core\Entity\ContentEntityInterface $entity */
+    $entity = $value;
+    if ($entity->isNew() || !$entity->getEntityType()->isRevisionable()) {
+      return;
+    }
+    // When changes to untranslatable fields are configured to affect all
+    // revision translations, we always allow changes in default revisions.
+    if ($entity->isDefaultRevision() && !$entity->isDefaultTranslationAffectedOnly()) {
+      return;
+    }
+    $entity_type_id = $entity->getEntityTypeId();
+    if (!$this->contentTranslationManager->isEnabled($entity_type_id, $entity->bundle())) {
+      return;
+    }
+    $synchronized_properties = $this->getSynchronizedPropertiesByField($entity->getFieldDefinitions());
+    if (!$synchronized_properties) {
+      return;
+    }
+
+    /** @var \Drupal\Core\Entity\ContentEntityInterface $original */
+    $original = $this->getOriginalEntity($entity);
+    $original_translation = $this->getOriginalTranslation($entity, $original);
+    if ($this->hasSynchronizedPropertyChanges($entity, $original_translation, $synchronized_properties)) {
+      if ($entity->isDefaultTranslationAffectedOnly()) {
+        foreach ($entity->getTranslationLanguages(FALSE) as $langcode => $language) {
+          if ($entity->getTranslation($langcode)->hasTranslationChanges()) {
+            $this->context->addViolation($constraint->defaultTranslationMessage);
+            break;
+          }
+        }
+      }
+      else {
+        $this->context->addViolation($constraint->defaultRevisionMessage);
+      }
+    }
+  }
+
+  /**
+   * Checks whether any synchronized property has changes.
+   *
+   * @param \Drupal\Core\Entity\ContentEntityInterface $entity
+   *   The entity being validated.
+   * @param \Drupal\Core\Entity\ContentEntityInterface $original
+   *   The original unchanged entity.
+   * @param string[][] $synchronized_properties
+   *   An associative array of arrays of synchronized field properties keyed by
+   *   field name.
+   *
+   * @return bool
+   *   TRUE if changes in synchronized properties were detected, FALSE
+   *   otherwise.
+   */
+  protected function hasSynchronizedPropertyChanges(ContentEntityInterface $entity, ContentEntityInterface $original, array $synchronized_properties) {
+    foreach ($synchronized_properties as $field_name => $properties) {
+      foreach ($properties as $property) {
+        $items = $entity->get($field_name)->getValue();
+        $original_items = $original->get($field_name)->getValue();
+        if (count($items) !== count($original_items)) {
+          return TRUE;
+        }
+        foreach ($items as $delta => $item) {
+          // @todo This loose comparison is not fully reliable. Revisit this
+          //   after https://www.drupal.org/project/drupal/issues/2941092.
+          if ($items[$delta][$property] != $original_items[$delta][$property]) {
+            return TRUE;
+          }
+        }
+      }
+    }
+    return FALSE;
+  }
+
+  /**
+   * Returns the original unchanged entity to be used to detect changes.
+   *
+   * @param \Drupal\Core\Entity\ContentEntityInterface $entity
+   *   The entity being changed.
+   *
+   * @return \Drupal\Core\Entity\ContentEntityInterface
+   *   The unchanged entity.
+   */
+  protected function getOriginalEntity(ContentEntityInterface $entity) {
+    if (!isset($entity->original)) {
+      $storage = $this->entityTypeManager->getStorage($entity->getEntityTypeId());
+      $original = $entity->isDefaultRevision() ? $storage->loadUnchanged($entity->id()) : $storage->loadRevision($entity->getLoadedRevisionId());
+    }
+    else {
+      $original = $entity->original;
+    }
+    return $original;
+  }
+
+  /**
+   * Returns the original translation.
+   *
+   * @param \Drupal\Core\Entity\ContentEntityInterface $entity
+   *   The entity being validated.
+   * @param \Drupal\Core\Entity\ContentEntityInterface $original
+   *   The original entity.
+   *
+   * @return \Drupal\Core\Entity\ContentEntityInterface
+   *   The original entity translation object.
+   */
+  protected function getOriginalTranslation(ContentEntityInterface $entity, ContentEntityInterface $original) {
+    $langcode = $entity->language()->getId();
+    if ($original->hasTranslation($langcode)) {
+      $original_langcode = $langcode;
+    }
+    else {
+      $metadata = $this->contentTranslationManager->getTranslationMetadata($entity);
+      $original_langcode = $metadata->getSource();
+    }
+    return $original->getTranslation($original_langcode);
+  }
+
+  /**
+   * Returns the synchronized properties for every specified field.
+   *
+   * @param \Drupal\Core\Field\FieldDefinitionInterface[] $field_definitions
+   *   An array of field definitions.
+   *
+   * @return string[][]
+   *   An associative array of arrays of field property names keyed by field
+   *   name.
+   */
+  public function getSynchronizedPropertiesByField(array $field_definitions) {
+    $synchronizer = $this->synchronizer;
+    $synchronized_properties = array_filter(array_map(
+      function (FieldDefinitionInterface $field_definition) use ($synchronizer) {
+        return $synchronizer->getFieldSynchronizedProperties($field_definition);
+      },
+      $field_definitions
+    ));
+    return $synchronized_properties;
+  }
+
+}
diff --git a/core/modules/content_translation/tests/modules/content_translation_test/content_translation_test.module b/core/modules/content_translation/tests/modules/content_translation_test/content_translation_test.module
index d1f321b59c604eebfdd6d1425bd3f0f6e7d620bf..50495a8c799b202413954134d27803e6f8fc89ca 100644
--- a/core/modules/content_translation/tests/modules/content_translation_test/content_translation_test.module
+++ b/core/modules/content_translation/tests/modules/content_translation_test/content_translation_test.module
@@ -5,7 +5,10 @@
  * Helper module for the Content Translation tests.
  */
 
+use Drupal\Core\Access\AccessResult;
+use Drupal\Core\Entity\EntityInterface;
 use Drupal\Core\Form\FormStateInterface;
+use Drupal\Core\Session\AccountInterface;
 
 /**
  * Implements hook_entity_bundle_info_alter().
@@ -23,6 +26,19 @@ function content_translation_test_entity_bundle_info_alter(&$bundles) {
   }
 }
 
+/**
+ * Implements hook_entity_access().
+ */
+function content_translation_test_entity_access(EntityInterface $entity, $operation, AccountInterface $account) {
+  $access = \Drupal::state()->get('content_translation.entity_access.' . $entity->getEntityTypeId());
+  if (!empty($access[$operation])) {
+    return AccessResult::allowed();
+  }
+  else {
+    return AccessResult::neutral();
+  }
+}
+
 /**
  * Implements hook_form_BASE_FORM_ID_alter().
  *
diff --git a/core/modules/content_translation/tests/src/Kernel/ContentTranslationFieldSyncRevisionTest.php b/core/modules/content_translation/tests/src/Kernel/ContentTranslationFieldSyncRevisionTest.php
new file mode 100644
index 0000000000000000000000000000000000000000..8185182516c7bd4b7942f7f7bf529690d68a879e
--- /dev/null
+++ b/core/modules/content_translation/tests/src/Kernel/ContentTranslationFieldSyncRevisionTest.php
@@ -0,0 +1,482 @@
+<?php
+
+namespace Drupal\Tests\content_translation\Kernel;
+
+use Drupal\Core\Entity\ContentEntityInterface;
+use Drupal\Core\Entity\EntityConstraintViolationListInterface;
+use Drupal\Core\Language\LanguageInterface;
+use Drupal\entity_test\Entity\EntityTestMulRev;
+use Drupal\field\Entity\FieldConfig;
+use Drupal\field\Entity\FieldStorageConfig;
+use Drupal\file\Entity\File;
+use Drupal\KernelTests\Core\Entity\EntityKernelTestBase;
+use Drupal\language\Entity\ConfigurableLanguage;
+use Drupal\Tests\TestFileCreationTrait;
+use Drupal\user\Entity\User;
+
+/**
+ * Tests the field synchronization logic when revisions are involved.
+ *
+ * @group content_translation
+ */
+class ContentTranslationFieldSyncRevisionTest extends EntityKernelTestBase {
+
+  use TestFileCreationTrait;
+
+  /**
+   * {@inheritdoc}
+   */
+  public static $modules = ['file', 'image', 'language', 'content_translation', 'simpletest', 'content_translation_test'];
+
+  /**
+   * The synchronized field name.
+   *
+   * @var string
+   */
+  protected $fieldName = 'sync_field';
+
+  /**
+   * The content translation manager.
+   *
+   * @var \Drupal\content_translation\ContentTranslationManagerInterface|\Drupal\content_translation\BundleTranslationSettingsInterface
+   */
+  protected $contentTranslationManager;
+
+  /**
+   * The test entity storage.
+   *
+   * @var \Drupal\Core\Entity\ContentEntityStorageInterface
+   */
+  protected $storage;
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp() {
+    parent::setUp();
+
+    $entity_type_id = 'entity_test_mulrev';
+    $this->installEntitySchema($entity_type_id);
+    $this->installEntitySchema('file');
+    $this->installSchema('file', ['file_usage']);
+
+    ConfigurableLanguage::createFromLangcode('it')->save();
+    ConfigurableLanguage::createFromLangcode('fr')->save();
+
+    /** @var \Drupal\field\Entity\FieldStorageConfig $field_storage */
+    $field_storage_config = FieldStorageConfig::create([
+      'field_name' => $this->fieldName,
+      'type' => 'image',
+      'entity_type' => $entity_type_id,
+      'cardinality' => 1,
+      'translatable' => 1,
+    ]);
+    $field_storage_config->save();
+
+    $field_config = FieldConfig::create([
+      'entity_type' => $entity_type_id,
+      'field_name' => $this->fieldName,
+      'bundle' => $entity_type_id,
+      'label' => 'Synchronized field',
+      'translatable' => 1,
+    ]);
+    $field_config->save();
+
+    $property_settings = [
+      'alt' => 'alt',
+      'title' => 'title',
+      'file' => 0,
+    ];
+    $field_config->setThirdPartySetting('content_translation', 'translation_sync', $property_settings);
+    $field_config->save();
+
+    $this->entityManager->clearCachedDefinitions();
+
+    $this->contentTranslationManager = $this->container->get('content_translation.manager');
+    $this->contentTranslationManager->setEnabled($entity_type_id, $entity_type_id, TRUE);
+
+    $this->storage = $this->entityManager->getStorage($entity_type_id);
+
+    foreach ($this->getTestFiles('image') as $file) {
+      $entity = File::create((array) $file + ['status' => 1]);
+      $entity->save();
+    }
+
+    $this->state->set('content_translation.entity_access.file', ['view' => TRUE]);
+
+    $account = User::create([
+      'name' => $this->randomMachineName(),
+      'status' => 1,
+    ]);
+    $account->save();
+  }
+
+  /**
+   * Checks that field synchronization works as expected with revisions.
+   *
+   * @covers \Drupal\content_translation\Plugin\Validation\Constraint\ContentTranslationSynchronizedFieldsConstraintValidator::create
+   * @covers \Drupal\content_translation\Plugin\Validation\Constraint\ContentTranslationSynchronizedFieldsConstraintValidator::validate
+   * @covers \Drupal\content_translation\Plugin\Validation\Constraint\ContentTranslationSynchronizedFieldsConstraintValidator::hasSynchronizedPropertyChanges
+   * @covers \Drupal\content_translation\FieldTranslationSynchronizer::getFieldSynchronizedProperties
+   * @covers \Drupal\content_translation\FieldTranslationSynchronizer::synchronizeFields
+   * @covers \Drupal\content_translation\FieldTranslationSynchronizer::synchronizeItems
+   */
+  public function testFieldSynchronizationAndValidation() {
+    // Test that when untranslatable field widgets are displayed, synchronized
+    // field properties can be changed only in default revisions.
+    $this->setUntranslatableFieldWidgetsDisplay(TRUE);
+    $entity = $this->saveNewEntity();
+    $entity_id = $entity->id();
+    $this->assertLatestRevisionFieldValues($entity_id, [1, 1, 1, 'Alt 1 EN']);
+
+    /** @var \Drupal\Core\Entity\ContentEntityInterface $en_revision */
+    $en_revision = $this->createRevision($entity, FALSE);
+    $en_revision->get($this->fieldName)->target_id = 2;
+    $violations = $en_revision->validate();
+    $this->assertViolations($violations);
+
+    $it_translation = $entity->addTranslation('it', $entity->toArray());
+    /** @var \Drupal\Core\Entity\ContentEntityInterface $it_revision */
+    $it_revision = $this->createRevision($it_translation, FALSE);
+    $metadata = $this->contentTranslationManager->getTranslationMetadata($it_revision);
+    $metadata->setSource('en');
+    $it_revision->get($this->fieldName)->target_id = 2;
+    $it_revision->get($this->fieldName)->alt = 'Alt 2 IT';
+    $violations = $it_revision->validate();
+    $this->assertViolations($violations);
+    $it_revision->isDefaultRevision(TRUE);
+    $violations = $it_revision->validate();
+    $this->assertEmpty($violations);
+    $this->storage->save($it_revision);
+    $this->assertLatestRevisionFieldValues($entity_id, [2, 2, 2, 'Alt 1 EN', 'Alt 2 IT']);
+
+    $en_revision = $this->createRevision($en_revision, FALSE);
+    $en_revision->get($this->fieldName)->alt = 'Alt 3 EN';
+    $violations = $en_revision->validate();
+    $this->assertEmpty($violations);
+    $this->storage->save($en_revision);
+    $this->assertLatestRevisionFieldValues($entity_id, [3, 2, 2, 'Alt 3 EN', 'Alt 2 IT']);
+
+    $it_revision = $this->createRevision($it_revision, FALSE);
+    $it_revision->get($this->fieldName)->alt = 'Alt 4 IT';
+    $violations = $it_revision->validate();
+    $this->assertEmpty($violations);
+    $this->storage->save($it_revision);
+    $this->assertLatestRevisionFieldValues($entity_id, [4, 2, 2, 'Alt 1 EN', 'Alt 4 IT']);
+
+    $en_revision = $this->createRevision($en_revision);
+    $en_revision->get($this->fieldName)->alt = 'Alt 5 EN';
+    $violations = $en_revision->validate();
+    $this->assertEmpty($violations);
+    $this->storage->save($en_revision);
+    $this->assertLatestRevisionFieldValues($entity_id, [5, 2, 2, 'Alt 5 EN', 'Alt 2 IT']);
+
+    $en_revision = $this->createRevision($en_revision);
+    $en_revision->get($this->fieldName)->target_id = 6;
+    $en_revision->get($this->fieldName)->alt = 'Alt 6 EN';
+    $violations = $en_revision->validate();
+    $this->assertEmpty($violations);
+    $this->storage->save($en_revision);
+    $this->assertLatestRevisionFieldValues($entity_id, [6, 6, 6, 'Alt 6 EN', 'Alt 2 IT']);
+
+    $it_revision = $this->createRevision($it_revision);
+    $it_revision->get($this->fieldName)->alt = 'Alt 7 IT';
+    $violations = $it_revision->validate();
+    $this->assertEmpty($violations);
+    $this->storage->save($it_revision);
+    $this->assertLatestRevisionFieldValues($entity_id, [7, 6, 6, 'Alt 6 EN', 'Alt 7 IT']);
+
+    // Test that when untranslatable field widgets are hidden, synchronized
+    // field properties can be changed only when editing the default
+    // translation. This may lead to temporarily desynchronized values, when
+    // saving a pending revision for the default translation that changes a
+    // synchronized property (see revision 11).
+    $this->setUntranslatableFieldWidgetsDisplay(FALSE);
+    $entity = $this->saveNewEntity();
+    $entity_id = $entity->id();
+    $this->assertLatestRevisionFieldValues($entity_id, [8, 1, 1, 'Alt 1 EN']);
+
+    /** @var \Drupal\Core\Entity\ContentEntityInterface $en_revision */
+    $en_revision = $this->createRevision($entity, FALSE);
+    $en_revision->get($this->fieldName)->target_id = 2;
+    $en_revision->get($this->fieldName)->alt = 'Alt 2 EN';
+    $violations = $en_revision->validate();
+    $this->assertEmpty($violations);
+    $this->storage->save($en_revision);
+    $this->assertLatestRevisionFieldValues($entity_id, [9, 2, 2, 'Alt 2 EN']);
+
+    $it_translation = $entity->addTranslation('it', $entity->toArray());
+    /** @var \Drupal\Core\Entity\ContentEntityInterface $it_revision */
+    $it_revision = $this->createRevision($it_translation, FALSE);
+    $metadata = $this->contentTranslationManager->getTranslationMetadata($it_revision);
+    $metadata->setSource('en');
+    $it_revision->get($this->fieldName)->target_id = 3;
+    $violations = $it_revision->validate();
+    $this->assertViolations($violations);
+    $it_revision->isDefaultRevision(TRUE);
+    $violations = $it_revision->validate();
+    $this->assertViolations($violations);
+
+    $it_revision = $this->createRevision($it_translation);
+    $metadata = $this->contentTranslationManager->getTranslationMetadata($it_revision);
+    $metadata->setSource('en');
+    $it_revision->get($this->fieldName)->alt = 'Alt 3 IT';
+    $violations = $it_revision->validate();
+    $this->assertEmpty($violations);
+    $this->storage->save($it_revision);
+    $this->assertLatestRevisionFieldValues($entity_id, [10, 1, 1, 'Alt 1 EN', 'Alt 3 IT']);
+
+    $en_revision = $this->createRevision($en_revision, FALSE);
+    $en_revision->get($this->fieldName)->alt = 'Alt 4 EN';
+    $violations = $en_revision->validate();
+    $this->assertEmpty($violations);
+    $this->storage->save($en_revision);
+    $this->assertLatestRevisionFieldValues($entity_id, [11, 2, 1, 'Alt 4 EN', 'Alt 3 IT']);
+
+    $it_revision = $this->createRevision($it_revision, FALSE);
+    $it_revision->get($this->fieldName)->alt = 'Alt 5 IT';
+    $violations = $it_revision->validate();
+    $this->assertEmpty($violations);
+    $this->storage->save($it_revision);
+    $this->assertLatestRevisionFieldValues($entity_id, [12, 1, 1, 'Alt 1 EN', 'Alt 5 IT']);
+
+    $en_revision = $this->createRevision($en_revision);
+    $en_revision->get($this->fieldName)->target_id = 6;
+    $en_revision->get($this->fieldName)->alt = 'Alt 6 EN';
+    $violations = $en_revision->validate();
+    $this->assertEmpty($violations);
+    $this->storage->save($en_revision);
+    $this->assertLatestRevisionFieldValues($entity_id, [13, 6, 6, 'Alt 6 EN', 'Alt 3 IT']);
+
+    $it_revision = $this->createRevision($it_revision);
+    $it_revision->get($this->fieldName)->target_id = 7;
+    $violations = $it_revision->validate();
+    $this->assertViolations($violations);
+
+    $it_revision = $this->createRevision($it_revision);
+    $it_revision->get($this->fieldName)->alt = 'Alt 7 IT';
+    $violations = $it_revision->validate();
+    $this->assertEmpty($violations);
+    $this->storage->save($it_revision);
+    $this->assertLatestRevisionFieldValues($entity_id, [14, 6, 6, 'Alt 6 EN', 'Alt 7 IT']);
+
+    // Test that creating a default revision starting from a pending revision
+    // having changes to synchronized properties, without introducing new
+    // changes works properly.
+    $this->setUntranslatableFieldWidgetsDisplay(FALSE);
+    $entity = $this->saveNewEntity();
+    $entity_id = $entity->id();
+    $this->assertLatestRevisionFieldValues($entity_id, [15, 1, 1, 'Alt 1 EN']);
+
+    $it_translation = $entity->addTranslation('it', $entity->toArray());
+    /** @var \Drupal\Core\Entity\ContentEntityInterface $it_revision */
+    $it_revision = $this->createRevision($it_translation);
+    $metadata = $this->contentTranslationManager->getTranslationMetadata($it_revision);
+    $metadata->setSource('en');
+    $it_revision->get($this->fieldName)->alt = 'Alt 2 IT';
+    $violations = $it_revision->validate();
+    $this->assertEmpty($violations);
+    $this->storage->save($it_revision);
+    $this->assertLatestRevisionFieldValues($entity_id, [16, 1, 1, 'Alt 1 EN', 'Alt 2 IT']);
+
+    /** @var \Drupal\Core\Entity\ContentEntityInterface $en_revision */
+    $en_revision = $this->createRevision($entity);
+    $en_revision->get($this->fieldName)->target_id = 3;
+    $en_revision->get($this->fieldName)->alt = 'Alt 3 EN';
+    $violations = $en_revision->validate();
+    $this->assertEmpty($violations);
+    $this->storage->save($en_revision);
+    $this->assertLatestRevisionFieldValues($entity_id, [17, 3, 3, 'Alt 3 EN', 'Alt 2 IT']);
+
+    $en_revision = $this->createRevision($entity, FALSE);
+    $en_revision->get($this->fieldName)->target_id = 4;
+    $en_revision->get($this->fieldName)->alt = 'Alt 4 EN';
+    $violations = $en_revision->validate();
+    $this->assertEmpty($violations);
+    $this->storage->save($en_revision);
+    $this->assertLatestRevisionFieldValues($entity_id, [18, 4, 3, 'Alt 4 EN', 'Alt 2 IT']);
+
+    $en_revision = $this->createRevision($entity);
+    $violations = $en_revision->validate();
+    $this->assertEmpty($violations);
+    $this->storage->save($en_revision);
+    $this->assertLatestRevisionFieldValues($entity_id, [19, 4, 4, 'Alt 4 EN', 'Alt 2 IT']);
+
+    $it_revision = $this->createRevision($it_revision);
+    $it_revision->get($this->fieldName)->alt = 'Alt 6 IT';
+    $violations = $it_revision->validate();
+    $this->assertEmpty($violations);
+    $this->storage->save($it_revision);
+    $this->assertLatestRevisionFieldValues($entity_id, [20, 4, 4, 'Alt 4 EN', 'Alt 6 IT']);
+
+    // Check that we are not allowed to perform changes to multiple translations
+    // in pending revisions when synchronized properties are involved.
+    $this->setUntranslatableFieldWidgetsDisplay(FALSE);
+    $entity = $this->saveNewEntity();
+    $entity_id = $entity->id();
+    $this->assertLatestRevisionFieldValues($entity_id, [21, 1, 1, 'Alt 1 EN']);
+
+    $it_translation = $entity->addTranslation('it', $entity->toArray());
+    /** @var \Drupal\Core\Entity\ContentEntityInterface $it_revision */
+    $it_revision = $this->createRevision($it_translation);
+    $metadata = $this->contentTranslationManager->getTranslationMetadata($it_revision);
+    $metadata->setSource('en');
+    $it_revision->get($this->fieldName)->alt = 'Alt 2 IT';
+    $violations = $it_revision->validate();
+    $this->assertEmpty($violations);
+    $this->storage->save($it_revision);
+    $this->assertLatestRevisionFieldValues($entity_id, [22, 1, 1, 'Alt 1 EN', 'Alt 2 IT']);
+
+    $en_revision = $this->createRevision($entity, FALSE);
+    $en_revision->get($this->fieldName)->target_id = 2;
+    $en_revision->getTranslation('it')->get($this->fieldName)->alt = 'Alt 3 IT';
+    $violations = $en_revision->validate();
+    $this->assertViolations($violations);
+
+    // Test that when saving a new default revision starting from a pending
+    // revision, outdated synchronized properties do not override more recent
+    // ones.
+    $this->setUntranslatableFieldWidgetsDisplay(TRUE);
+    $entity = $this->saveNewEntity();
+    $entity_id = $entity->id();
+    $this->assertLatestRevisionFieldValues($entity_id, [23, 1, 1, 'Alt 1 EN']);
+
+    $it_translation = $entity->addTranslation('it', $entity->toArray());
+    /** @var \Drupal\Core\Entity\ContentEntityInterface $it_revision */
+    $it_revision = $this->createRevision($it_translation, FALSE);
+    $metadata = $this->contentTranslationManager->getTranslationMetadata($it_revision);
+    $metadata->setSource('en');
+    $it_revision->get($this->fieldName)->alt = 'Alt 2 IT';
+    $violations = $it_revision->validate();
+    $this->assertEmpty($violations);
+    $this->storage->save($it_revision);
+    $this->assertLatestRevisionFieldValues($entity_id, [24, 1, 1, 'Alt 1 EN', 'Alt 2 IT']);
+
+    /** @var \Drupal\Core\Entity\ContentEntityInterface $en_revision */
+    $en_revision = $this->createRevision($entity);
+    $en_revision->get($this->fieldName)->target_id = 3;
+    $en_revision->get($this->fieldName)->alt = 'Alt 3 EN';
+    $violations = $en_revision->validate();
+    $this->assertEmpty($violations);
+    $this->storage->save($en_revision);
+    $this->assertLatestRevisionFieldValues($entity_id, [25, 3, 3, 'Alt 3 EN', 'Alt 2 IT']);
+
+    $it_revision = $this->createRevision($it_revision);
+    $it_revision->get($this->fieldName)->alt = 'Alt 4 IT';
+    $violations = $it_revision->validate();
+    $this->assertEmpty($violations);
+    $this->storage->save($it_revision);
+    $this->assertLatestRevisionFieldValues($entity_id, [26, 3, 3, 'Alt 3 EN', 'Alt 4 IT']);
+  }
+
+  /**
+   * Sets untranslatable field widgets' display status.
+   *
+   * @param bool $display
+   *   Whether untranslatable field widgets should be displayed.
+   */
+  protected function setUntranslatableFieldWidgetsDisplay($display) {
+    $entity_type_id = $this->storage->getEntityTypeId();
+    $settings = ['untranslatable_fields_hide' => !$display];
+    $this->contentTranslationManager->setBundleTranslationSettings($entity_type_id, $entity_type_id, $settings);
+    /** @var \Drupal\Core\Entity\EntityTypeBundleInfo $bundle_info */
+    $bundle_info = $this->container->get('entity_type.bundle.info');
+    $bundle_info->clearCachedBundles();
+  }
+
+  /**
+   * @return \Drupal\Core\Entity\ContentEntityInterface
+   */
+  protected function saveNewEntity() {
+    /** @var \Drupal\Core\Entity\ContentEntityInterface $entity */
+    $entity = EntityTestMulRev::create([
+      'uid' => 1,
+      'langcode' => 'en',
+      $this->fieldName => [
+        'target_id' => 1,
+        'alt' => 'Alt 1 EN',
+      ],
+    ]);
+    $metadata = $this->contentTranslationManager->getTranslationMetadata($entity);
+    $metadata->setSource(LanguageInterface::LANGCODE_NOT_SPECIFIED);
+    $violations = $entity->validate();
+    $this->assertEmpty($violations);
+    $this->storage->save($entity);
+    return $entity;
+  }
+
+  /**
+   * Creates a new revision starting from the latest translation-affecting one.
+   *
+   * @param \Drupal\Core\Entity\ContentEntityInterface $translation
+   *   The translation to be revisioned.
+   * @param bool $default
+   *   (optional) Whether the new revision should be marked as default. Defaults
+   *   to TRUE.
+   *
+   * @return \Drupal\Core\Entity\ContentEntityInterface
+   *   An entity revision object.
+   */
+  protected function createRevision(ContentEntityInterface $translation, $default = TRUE) {
+    if (!$translation->isNewTranslation()) {
+      $langcode = $translation->language()->getId();
+      $revision_id = $this->storage->getLatestTranslationAffectedRevisionId($translation->id(), $langcode);
+      /** @var \Drupal\Core\Entity\ContentEntityInterface $revision */
+      $revision = $this->storage->loadRevision($revision_id);
+      $translation = $revision->getTranslation($langcode);
+    }
+    /** @var \Drupal\Core\Entity\ContentEntityInterface $revision */
+    $revision = $this->storage->createRevision($translation, $default);
+    return $revision;
+  }
+
+  /**
+   * Asserts that the expected violations were found.
+   *
+   * @param \Drupal\Core\Entity\EntityConstraintViolationListInterface $violations
+   *   A list of violations.
+   */
+  protected function assertViolations(EntityConstraintViolationListInterface $violations) {
+    $entity_type_id = $this->storage->getEntityTypeId();
+    $settings = $this->contentTranslationManager->getBundleTranslationSettings($entity_type_id, $entity_type_id);
+    $message = !empty($settings['untranslatable_fields_hide']) ?
+      'Non-translatable field elements can only be changed when updating the original language.' :
+      'Non-translatable field elements can only be changed when updating the current revision.';
+
+    $list = [];
+    foreach ($violations as $violation) {
+      if ((string) $violation->getMessage() === $message) {
+        $list[] = $violation;
+      }
+    }
+    $this->assertCount(1, $list);
+  }
+
+  /**
+   * Asserts that the latest revision has the expected field values.
+   *
+   * @param $entity_id
+   *   The entity ID.
+   * @param array $expected_values
+   *   An array of expected values in the following order:
+   *   - revision ID
+   *   - target ID (en)
+   *   - target ID (it)
+   *   - alt (en)
+   *   - alt (it)
+   */
+  protected function assertLatestRevisionFieldValues($entity_id, array $expected_values) {
+    /** @var \Drupal\Core\Entity\ContentEntityInterface $entity */
+    $entity = $this->storage->loadRevision($this->storage->getLatestRevisionId($entity_id));
+    @list($revision_id, $target_id_en, $target_id_it, $alt_en, $alt_it) = $expected_values;
+    $this->assertEquals($revision_id, $entity->getRevisionId());
+    $this->assertEquals($target_id_en, $entity->get($this->fieldName)->target_id);
+    $this->assertEquals($alt_en, $entity->get($this->fieldName)->alt);
+    if ($entity->hasTranslation('it')) {
+      $it_translation = $entity->getTranslation('it');
+      $this->assertEquals($target_id_it, $it_translation->get($this->fieldName)->target_id);
+      $this->assertEquals($alt_it, $it_translation->get($this->fieldName)->alt);
+    }
+  }
+
+}
diff --git a/core/modules/content_translation/tests/src/Kernel/ContentTranslationSyncUnitTest.php b/core/modules/content_translation/tests/src/Kernel/ContentTranslationSyncUnitTest.php
index fa5fd1c9b780f4edb5cfb1d5af7c97f921ff8df0..5c4784aa62e601d3df9c171063b36144d1f8e9e1 100644
--- a/core/modules/content_translation/tests/src/Kernel/ContentTranslationSyncUnitTest.php
+++ b/core/modules/content_translation/tests/src/Kernel/ContentTranslationSyncUnitTest.php
@@ -59,7 +59,7 @@ class ContentTranslationSyncUnitTest extends KernelTestBase {
   protected function setUp() {
     parent::setUp();
 
-    $this->synchronizer = new FieldTranslationSynchronizer($this->container->get('entity.manager'));
+    $this->synchronizer = new FieldTranslationSynchronizer($this->container->get('entity.manager'), $this->container->get('plugin.manager.field.field_type'));
     $this->synchronized = ['sync1', 'sync2'];
     $this->columns = array_merge($this->synchronized, ['var1', 'var2']);
     $this->langcodes = ['en', 'it', 'fr', 'de', 'es'];