diff --git a/core/modules/migrate_drupal_ui/src/Form/CredentialForm.php b/core/modules/migrate_drupal_ui/src/Form/CredentialForm.php
index f272e7e6cf..64ba59e42e 100644
--- a/core/modules/migrate_drupal_ui/src/Form/CredentialForm.php
+++ b/core/modules/migrate_drupal_ui/src/Form/CredentialForm.php
@@ -195,17 +195,17 @@ public function validateForm(array &$form, FormStateInterface $form_state) {
     // Cut the trailing \Install from namespace.
     $database['namespace'] = substr($install_namespace, 0, strrpos($install_namespace, '\\'));
     $database['driver'] = $driver;
-    
+
     $errors = $drivers[$driver]->validateDatabaseSettings($database);
 
     try {
       $connection = $this->getConnection($database);
       $version = (string) $this->getLegacyDrupalVersion($connection);
       if (!$version) {
-        $errors['driver' . '][0'] = $this->t('Source database does not contain a recognizable Drupal version.');
+        $errors[$driver . '][0'] = $this->t('Source database does not contain a recognizable Drupal version.');
       }
       elseif ($version !== (string) $form_state->getValue('version')) {
-        $errors['driver' . '][0'] = $this->t('Source database is Drupal version @version but version @selected was selected.',
+        $errors[$driver . '][0'] = $this->t('Source database is Drupal version @version but version @selected was selected.',
           [
             '@version' => $version,
             '@selected' => $form_state->getValue('version'),
@@ -217,7 +217,7 @@ public function validateForm(array &$form, FormStateInterface $form_state) {
       }
     }
     catch (\Exception $e) {
-      $errors['driver' . '][0'] = $e->getMessage();
+      $errors[$driver . '][0'] = $e->getMessage();
     }
 
     // Check that sources files are available.
@@ -262,7 +262,7 @@ public function validateForm(array &$form, FormStateInterface $form_state) {
    * @param \Drupal\Core\Form\FormStateInterface $form_state
    *   The form state.
    */
-  protected function buildErrorList($errors, FormStateInterface $form_state) {
+  protected function buildErrorList(array $errors, FormStateInterface $form_state) {
     $items = [];
     foreach ($errors as $name => $message) {
       $form_state->setErrorByName($name);