Issue #3485182: Moved the message code after clear cache code.

src/Controller/NavigationExtraToolsController.php

@@ -104,8 +104,8 @@ final class NavigationExtraToolsController extends ControllerBase {
    * Flushes all caches.
    */
   public function flushAll() {
-    $this->messenger()->addMessage($this->t('All caches cleared.'));
     drupal_flush_all_caches();
+    $this->messenger()->addMessage($this->t('All caches cleared.'));
     return new RedirectResponse($this->reloadPage());
   }