diff -u b/core/modules/field/src/Entity/FieldStorageConfig.php b/core/modules/field/src/Entity/FieldStorageConfig.php
--- b/core/modules/field/src/Entity/FieldStorageConfig.php
+++ b/core/modules/field/src/Entity/FieldStorageConfig.php
@@ -255,11 +255,6 @@
     }
 
     parent::__construct($values, $entity_type);
-
-    // @see \Drupal\Tests\options\Kernel\OptionsFieldTest::testReImportAllowedValues()
-    $field_item_class = $this->getFieldItemClass();
-    $this->settings = $field_item_class::storageSettingsToConfigData($this->settings);
-    $this->settings = $field_item_class::storageSettingsFromConfigData($this->settings);
   }
 
   /**
@@ -374,6 +369,11 @@
       throw new FieldException("Cannot change the entity type for an existing field storage.");
     }
 
+    // @see \Drupal\Tests\options\Kernel\OptionsFieldTest::testReImportAllowedValues()
+    $field_item_class = $this->getFieldItemClass();
+    $this->settings = $field_item_class::storageSettingsToConfigData($this->settings);
+    $this->settings = $field_item_class::storageSettingsFromConfigData($this->settings);
+
     // See if any module forbids the update by throwing an exception. This
     // invokes hook_field_storage_config_update_forbid().
     $module_handler->invokeAll('field_storage_config_update_forbid', array($this, $this->original));