Ошибка 500 на сайте

На сайте: http://noventa18.ru/ периодически выходит ошибка 500, в логах сайта:
2017-08-22 03:03:39.3961, Error, : The network path was not found
URL=[];
Referrer=[]
2017-08-22 03:55:35.4825, Error, : The wait operation timed out
URL=[];
Referrer=[]
2017-08-22 04:30:25.2411, Error, : A potentially dangerous Request.Path value was detected from the client (>).
URL=[/admin/userfiles/image/%3ED0%9A%D0%B0%D1%80%D1%82%D0%B8%D0%BD%D0%BA%D0%B8%20%D0%B4%D0%BB%D1%8F%20%D0%BD%D0%BE%D0%B2%D0%BE%D1%81%D1%82%D0%B5%D0%B9/44_(12)(1).jpg];
Referrer=[]...