调用Ajax返回500错误的解决方法

 1   public ActionResult UserLogin(LogOnModel model)
 2         {
 3             #region 验证码验证
 4             
 5             #endregion
 6 
 7            OperationResult result=   _identity.ValidateUser(model.UserName, EncryptAndDecrypte.EncryptString(model.Password));
 8 
 9 
10            if (result.ResultType==OperationResultType.Success)
11             {   //登陆成功
12                 SysUser user = (SysUser) result.Data;
13                 //Account account = new Account
14                 //{
15                 //    PersonName = user.UserName,
16                 //    Name = user.NickName,
17                 //    Id = user.Id
18                 //};
19                 _sysAuthenticationService.SignIn(user,false);
20                // Utils.WriteCookie("account",account,7);
21 
22                 result.Data = null;
23             }
24 
25             return Json(result);
26         }