--- a/permissions_by_term/permissions_by_term.module
+++ b/permissions_by_term/permissions_by_term.module
@@ -308,7 +308,7 @@ function permissions_by_term_user_form_submit(array &$form, FormStateInterface $

   // Rebuild permissions for nodes if needed.
   $origTerms = $form['access']['terms']['#default_value'] ?? [];
-  $newTerms = $form_state->getValue('terms');
+  $newTerms = empty($form_state->getValue('terms')) ? [] : $form_state->getValue('terms');
   $changes = array_diff($origTerms, $newTerms) + array_diff($newTerms, $origTerms);

   if (!\Drupal::config('permissions_by_term.settings')->get('disable_node_access_records') &&