diff --cc core/modules/user/src/AccountForm.php
index 15df478,0f2e350..0000000
--- a/core/modules/user/src/AccountForm.php
+++ b/core/modules/user/src/AccountForm.php
@@@ -324,23 -328,33 +324,34 @@@ abstract class AccountForm extends Cont
      parent::validate($form, $form_state);
  
      $account = $this->entity;
 -    $mail = $form_state['values']['mail'];
++    $mail = $form_state->getValue('mail');
+ 
      // Validate new or changing username.
 -    if (isset($form_state['values']['name'])) {
 -      $name = $form_state['values']['name'];
 +    if ($form_state->hasValue('name')) {
-       if ($error = user_validate_name($form_state->getValue('name'))) {
++      $name = $form_state->getValue('name');
+ 
+       if ($error = user_validate_name($name)) {
 -        $this->setFormError('name', $form_state, $error);
 +        $form_state->setErrorByName('name', $error);
        }
        // Cast the user ID as an integer. It might have been set to NULL, which
        // could lead to unexpected results.
        else {
          $name_taken = (bool) $this->entityQuery->get('user')
            ->condition('uid', (int) $account->id(), '<>')
-           ->condition('name', $form_state->getValue('name'))
+           ->condition('name', $name)
++
            ->range(0, 1)
            ->count()
            ->execute();
  
          if ($name_taken) {
-           $form_state->setErrorByName('name', $this->t('The name %name is already taken.', array('%name' => $form_state->getValue('name'))));
 -          $this->setFormError('name', $form_state, $this->t('The name %name is already taken.', array('%name' => $name)));
++          $form_state->setErrorByName('name', $this->t('The name %name is already taken.', array('%name' => $name)));
+         }
+ 
+         // Check whether the user name provided is an email address, if so, make
+         // sure it matches the mail value.
+         if (\Drupal::config('user.settings')->get('verify_email_match') && (filter_var($name, FILTER_VALIDATE_EMAIL) && ($name !== $mail))) {
+           $this->setFormError('name', $form_state, $this->t('You have provided an e-mail address as a username, but this does not match your e-mail address.'));
          }
        }
      }
diff --cc core/modules/user/src/AccountSettingsForm.php
index 8fc998b,3daa69f..0000000
--- a/core/modules/user/src/AccountSettingsForm.php
+++ b/core/modules/user/src/AccountSettingsForm.php
@@@ -413,37 -416,38 +418,38 @@@ class AccountSettingsForm extends Confi
      parent::submitForm($form, $form_state);
  
      $this->config('user.settings')
 -      ->set('anonymous', $form_state['values']['anonymous'])
 -      ->set('admin_role', $form_state['values']['user_admin_role'])
 -      ->set('register', $form_state['values']['user_register'])
 -      ->set('password_strength', $form_state['values']['user_password_strength'])
 -      ->set('verify_mail', $form_state['values']['user_email_verification'])
 -      ->set('verify_email_match', $form_state['values']['user_email_match_verification'])
 -      ->set('signatures', $form_state['values']['user_signatures'])
 -      ->set('cancel_method', $form_state['values']['user_cancel_method'])
 -      ->set('notify.status_activated', $form_state['values']['user_mail_status_activated_notify'])
 -      ->set('notify.status_blocked', $form_state['values']['user_mail_status_blocked_notify'])
 -      ->set('notify.status_canceled', $form_state['values']['user_mail_status_canceled_notify'])
 +      ->set('anonymous', $form_state->getValue('anonymous'))
 +      ->set('admin_role', $form_state->getValue('user_admin_role'))
 +      ->set('register', $form_state->getValue('user_register'))
 +      ->set('password_strength', $form_state->getValue('user_password_strength'))
 +      ->set('verify_mail', $form_state->getValue('user_email_verification'))
++      ->set('verify_email_match', $form_state->getValue('user_email_match_verification'))
 +      ->set('signatures', $form_state->getValue('user_signatures'))
 +      ->set('cancel_method', $form_state->getValue('user_cancel_method'))
 +      ->set('notify.status_activated', $form_state->getValue('user_mail_status_activated_notify'))
 +      ->set('notify.status_blocked', $form_state->getValue('user_mail_status_blocked_notify'))
 +      ->set('notify.status_canceled', $form_state->getValue('user_mail_status_canceled_notify'))
        ->save();
      $this->config('user.mail')
 -      ->set('cancel_confirm.body', $form_state['values']['user_mail_cancel_confirm_body'])
 -      ->set('cancel_confirm.subject', $form_state['values']['user_mail_cancel_confirm_subject'])
 -      ->set('password_reset.body', $form_state['values']['user_mail_password_reset_body'])
 -      ->set('password_reset.subject', $form_state['values']['user_mail_password_reset_subject'])
 -      ->set('register_admin_created.body', $form_state['values']['user_mail_register_admin_created_body'])
 -      ->set('register_admin_created.subject', $form_state['values']['user_mail_register_admin_created_subject'])
 -      ->set('register_no_approval_required.body', $form_state['values']['user_mail_register_no_approval_required_body'])
 -      ->set('register_no_approval_required.subject', $form_state['values']['user_mail_register_no_approval_required_subject'])
 -      ->set('register_pending_approval.body', $form_state['values']['user_mail_register_pending_approval_body'])
 -      ->set('register_pending_approval.subject', $form_state['values']['user_mail_register_pending_approval_subject'])
 -      ->set('status_activated.body', $form_state['values']['user_mail_status_activated_body'])
 -      ->set('status_activated.subject', $form_state['values']['user_mail_status_activated_subject'])
 -      ->set('status_blocked.body', $form_state['values']['user_mail_status_blocked_body'])
 -      ->set('status_blocked.subject', $form_state['values']['user_mail_status_blocked_subject'])
 -      ->set('status_canceled.body', $form_state['values']['user_mail_status_canceled_body'])
 -      ->set('status_canceled.subject', $form_state['values']['user_mail_status_canceled_subject'])
 +      ->set('cancel_confirm.body', $form_state->getValue('user_mail_cancel_confirm_body'))
 +      ->set('cancel_confirm.subject', $form_state->getValue('user_mail_cancel_confirm_subject'))
 +      ->set('password_reset.body', $form_state->getValue('user_mail_password_reset_body'))
 +      ->set('password_reset.subject', $form_state->getValue('user_mail_password_reset_subject'))
 +      ->set('register_admin_created.body', $form_state->getValue('user_mail_register_admin_created_body'))
 +      ->set('register_admin_created.subject', $form_state->getValue('user_mail_register_admin_created_subject'))
 +      ->set('register_no_approval_required.body', $form_state->getValue('user_mail_register_no_approval_required_body'))
 +      ->set('register_no_approval_required.subject', $form_state->getValue('user_mail_register_no_approval_required_subject'))
 +      ->set('register_pending_approval.body', $form_state->getValue('user_mail_register_pending_approval_body'))
 +      ->set('register_pending_approval.subject', $form_state->getValue('user_mail_register_pending_approval_subject'))
 +      ->set('status_activated.body', $form_state->getValue('user_mail_status_activated_body'))
 +      ->set('status_activated.subject', $form_state->getValue('user_mail_status_activated_subject'))
 +      ->set('status_blocked.body', $form_state->getValue('user_mail_status_blocked_body'))
 +      ->set('status_blocked.subject', $form_state->getValue('user_mail_status_blocked_subject'))
 +      ->set('status_canceled.body', $form_state->getValue('user_mail_status_canceled_body'))
 +      ->set('status_canceled.subject', $form_state->getValue('user_mail_status_canceled_subject'))
        ->save();
      $this->config('system.site')
 -      ->set('mail_notification', $form_state['values']['mail_notification_address'])
 +      ->set('mail_notification', $form_state->getValue('mail_notification_address'))
        ->save();
    }