diff -u b/core/modules/field/lib/Drupal/field/Plugin/Core/Entity/Field.php b/core/modules/field/lib/Drupal/field/Plugin/Core/Entity/Field.php
--- b/core/modules/field/lib/Drupal/field/Plugin/Core/Entity/Field.php
+++ b/core/modules/field/lib/Drupal/field/Plugin/Core/Entity/Field.php
@@ -261,7 +261,16 @@
   }
 
   /**
-   * {@inheritdoc}
+   * Overrides \Drupal\Core\Entity\Entity::save().
+   *
+   * @return
+   *   Either SAVED_NEW or SAVED_UPDATED, depending on the operation performed.
+   *
+   * @throws \Drupal\field\FieldException
+   *   If the field definition is invalid.
+   *
+   * @throws \Drupal\Core\Entity\EntityStorageException
+   *   In case of failures at the configuration storage level.
    */
   public function save() {
     // Clear the derived data about the field.
@@ -281,8 +290,11 @@
    * @return
    *   SAVED_NEW if the definition was saved.
    *
+   * @throws \Drupal\field\FieldException
+   *   If the field definition is invalid.
+   *
    * @throws \Drupal\Core\Entity\EntityStorageException
-   *   In case of failures an exception is thrown.
+   *   In case of failures at the configuration storage level.
    */
   protected function saveNew() {
     $module_handler = \Drupal::moduleHandler();
@@ -365,8 +377,11 @@
    * @return
    *   SAVED_UPDATED if the definition was saved.
    *
+   * @throws \Drupal\field\FieldException
+   *   If the field definition is invalid.
+   *
    * @throws \Drupal\Core\Entity\EntityStorageException
-   *   In case of failures an exception is thrown.
+   *   In case of failures at the configuration storage level.
    */
   protected function saveUpdated() {
     $module_handler = \Drupal::moduleHandler();
diff -u b/core/modules/field/lib/Drupal/field/Plugin/Core/Entity/FieldInstance.php b/core/modules/field/lib/Drupal/field/Plugin/Core/Entity/FieldInstance.php
--- b/core/modules/field/lib/Drupal/field/Plugin/Core/Entity/FieldInstance.php
+++ b/core/modules/field/lib/Drupal/field/Plugin/Core/Entity/FieldInstance.php
@@ -316,7 +316,16 @@
   }
 
   /**
-   * {@inheritdoc}
+   * Overrides \Drupal\Core\Entity\Entity::save().
+   *
+   * @return
+   *   Either SAVED_NEW or SAVED_UPDATED, depending on the operation performed.
+   *
+   * @throws \Drupal\field\FieldException
+   *   If the field instance definition is invalid.
+   *
+   * @throws \Drupal\Core\Entity\EntityStorageException
+   *   In case of failures at the configuration storage level.
    */
   public function save() {
     if ($this->isNew()) {
@@ -333,8 +342,11 @@
    * @return
    *   SAVED_NEW if the definition was saved.
    *
+   * @throws \Drupal\field\FieldException
+   *   If the field instance definition is invalid.
+   *
    * @throws \Drupal\Core\Entity\EntityStorageException
-   *   In case of failures an exception is thrown.
+   *   In case of failures at the configuration storage level.
    */
   protected function saveNew() {
     $module_handler = \Drupal::moduleHandler();
@@ -377,8 +389,11 @@
    * @return
    *   SAVED_UPDATED if the definition was saved.
    *
+   * @throws \Drupal\field\FieldException
+   *   If the field instance definition is invalid.
+   *
    * @throws \Drupal\Core\Entity\EntityStorageException
-   *   In case of failures an exception is thrown.
+   *   In case of failures at the configuration storage level.
    */
   protected function saveUpdated() {
     $module_handler = \Drupal::moduleHandler();