preg match at backend side

				return $response;

			}

		}

		if (!preg_match('/^[a-zA-Z0-9._-]+$/', $username)) {

			$response->setData(['message' => 'Username must consist of letters, numbers, hyphens, dots and underscores only.', 'field' => 'username', 'success' => false]);

			$response->setStatus(403);

			return $response;

		}

		try {

			$username = mb_strtolower($username, 'UTF-8');

			if (!$this->userService->userExists($username) && !$this->userService->isUsernameTaken($username)) {