I got this error message when I try to submit a form with HTML Code, the default settings of the .NET Framework will not allow me to submit HTML Code to prevent cross-site scripting (XSS) attacks.
To avoid this error set Validate Request to false in the Page Directive.
ValidateRequest="false"
To avoid this error set Validate Request to false in the Page Directive.
ValidateRequest="false"
Source: https://www.nilebits.com/blog/2010/02/a-potentially-dangerous-request-form-value-was-detected-from-the-client-asp-net/
