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
@@ -1272,7 +1272,7 @@
 /**
  * Set langcode fields to be ASCII-only.
  */
-function system_update_8004() {
+function system_update_8005() {
   $database = \Drupal::database();
   $database_schema = $database->schema();