Aug 14, 2019 01:56 AM|Yang Shen|LINK
A potentially dangerous Request.Form value was detected from the client
Generally, this error message will point out where's wrong in your code at the end.
This error is usually caused by Script Attacks which you can refer to:Request-Validation.
In your case, please try add <pages validateRequest="false"></pages> in your web.config, which you can refer to here and here.