diff --git a/core/modules/block/src/BlockBase.php b/core/modules/block/src/BlockBase.php
index eb6b91d..707212e 100644
--- a/core/modules/block/src/BlockBase.php
+++ b/core/modules/block/src/BlockBase.php
@@ -344,6 +344,9 @@ public function blockForm($form, &$form_state) {
    * @see \Drupal\block\BlockBase::blockValidate()
    */
   public function validateConfigurationForm(array &$form, array &$form_state) {
+    // Remove the admin_label form item element value so it will not persist.
+    unset($form_state['values']['admin_label']);
+
     // Transform the #type = checkboxes value to a numerically indexed array.
     $form_state['values']['cache']['contexts'] = array_values(array_filter($form_state['values']['cache']['contexts']));