Issue #3239759: Remind users to back up their database before starting an update

src/Form/UpdateReady.php

@@ -162,7 +162,7 @@ class UpdateReady extends FormBase {
     ];
     $form['backup'] = [
       '#prefix' => '<strong>',
-      '#markup' => $this->t('It\'s a good idea to <a href=":url">back up your database</a> before you begin.', [':url' => 'https://www.drupal.org/node/22281#s-backing-up-the-database',]),
+      '#markup' => $this->t('This cannot be undone, so it is strongly recommended to <a href=":url">back up your database</a> before continuing, if you haven\'t already.', [':url' => 'https://www.drupal.org/node/22281#s-backing-up-the-database',]),
       '#suffix' => '</strong>',
     ];
     if (!$this->state->get('system.maintenance_mode')) {