注销后登录yclas？

Question

I logged out and now I can't log in to my yclas. There is nothing changed in my code but it logged this:

2018-12-20 01:12:29 --- ERROR: ErrorException [ 2 ]: preg_match(): Unknown 
modifier '?' ~ APPPATH\kohana\system\classes\Kohana\Valid.php [ 467 ] in 
C:\xampp\htdocs\main 
project\farmapp.lo\oc\kohana\system\classes\Kohana\Kohana\Exception.php:110