diff -u b/core/modules/system/system.install b/core/modules/system/system.install
--- b/core/modules/system/system.install
+++ b/core/modules/system/system.install
@@ -915,13 +915,13 @@
         'description' => 'Primary Key: Unique name.',
         'type' => 'varchar',
         'length' => 255,
+        'is_alphanumeric' => TRUE,
         'not null' => TRUE,
         'default' => ''
       ),
       'value' => array(
         'description' => 'A value for the semaphore.',
         'type' => 'varchar',
-        'is_alphanumeric' => TRUE,
         'length' => 255,
         'not null' => TRUE,
         'default' => ''
only in patch2:
unchanged:
--- a/core/lib/Drupal/Core/Field/Plugin/Field/FieldType/LanguageItem.php
+++ b/core/lib/Drupal/Core/Field/Plugin/Field/FieldType/LanguageItem.php
@@ -44,6 +44,7 @@ class LanguageItem extends FieldItemBase {
   public static function propertyDefinitions(FieldStorageDefinitionInterface $field_definition) {
     $properties['value'] = DataDefinition::create('string')
       ->setLabel(t('Language code'))
+      ->setSetting('is_alphanumeric', TRUE)
       ->setRequired(TRUE);
 
     $properties['language'] = DataReferenceDefinition::create('language')