Prevent users with dash in username - refs #7032

main/admin/user_import.php

@@ -56,6 +56,12 @@ function validate_data($users, $checkUniqueEmail = false)
                 $user['error'] = get_lang('UserNameTooLong');
                 $errors[] = $user;
             }
+            // 2.1.1
+            $hasDash = strpos($username, '-');
+            if ($hasDash !== false) {
+                $user['error'] = get_lang('UserNameHasDash');
+                $errors[] = $user;
+            }
             // 2.2. Check whether the username was used twice in import file.
             if (isset($usernames[$user['UserName']])) {
                 $user['error'] = get_lang('UserNameUsedTwice');