diff -u b/modules/ckeditor5/js/ckeditor5.js b/modules/ckeditor5/js/ckeditor5.js
--- b/modules/ckeditor5/js/ckeditor5.js
+++ b/modules/ckeditor5/js/ckeditor5.js
@@ -680,7 +680,8 @@
 
   // Respond to dialogs that are closed, removing the current save handler.
   $(window).on('dialog:afterclose', (e, dialog, element, dialogSettings) => {
-    const selector = dialogSettings.options.selector || '#drupal-modal';
+    const options = dialogSettings.options || {}
+    const selector = options.selector || '#drupal-modal';
     if (Drupal.ckeditor5.saveCallback.has(selector)) {
       Drupal.ckeditor5.saveCallback.delete(selector);
     }