diff -u b/core/lib/Drupal/Core/Render/Element/PasswordConfirm.php b/core/lib/Drupal/Core/Render/Element/PasswordConfirm.php
--- b/core/lib/Drupal/Core/Render/Element/PasswordConfirm.php
+++ b/core/lib/Drupal/Core/Render/Element/PasswordConfirm.php
@@ -117,7 +117,7 @@
     $pass1_not_trimmed = $element['pass1']['#value'];
     $pass1_size = strlen($element['pass1']['#value']);
     if ($pass1_size > 1) {
-      if ($pass1_not_trimmed[0] == " " || $pass1_not_trimmed[$pass1_size-1] == " ") {
+      if ($pass1_not_trimmed[0] == " " || $pass1_not_trimmed[$pass1_size - 1] == " ") {
         $form_state->setError($element, t('Whitespaces at the beginning or at the end of the password are not allowed.'));
       }
     }