diff -u b/core/modules/user/src/RegisterForm.php b/core/modules/user/src/RegisterForm.php
--- b/core/modules/user/src/RegisterForm.php
+++ b/core/modules/user/src/RegisterForm.php
@@ -122,7 +122,7 @@
       $this->messenger()->addStatus($this->t('Created a new user account for <a href=":url">%name</a>. No email has been sent.', [':url' => $account->toUrl()->toString(), '%name' => $account->getAccountName()]));
     }
     // E-mail verification enabled, but users set a password during registration.
-    elseif (!$admin && $config->get('register') == USER_REGISTER_VISITORS && $config->get('password_register') && !$account->isActive()) {
+    elseif (!$admin && $config->get('register') == UserInterface::REGISTER_VISITORS && $config->get('password_register') && !$account->isActive()) {
       // Notify the user.
       _user_mail_notify('register_password_set', $account);
       $this->messenger()->addStatus($this->t('A welcome message with further instructions has been sent to your email address.'));
diff -u b/core/modules/user/tests/src/Functional/UserRegistrationTest.php b/core/modules/user/tests/src/Functional/UserRegistrationTest.php
--- b/core/modules/user/tests/src/Functional/UserRegistrationTest.php
+++ b/core/modules/user/tests/src/Functional/UserRegistrationTest.php
@@ -145,7 +145,7 @@
     // and allow registration by site visitors without administrator approval.
     $this->config('user.settings')
       ->set('verify_mail', TRUE)
-      ->set('register', USER_REGISTER_VISITORS)
+      ->set('register', UserInterface::REGISTER_VISITORS)
       ->set('password_register', TRUE)
       ->save();