The following “yellow screen” error occurs in your application:
A potentially dangerous Request.QueryString value was detected from the client ...
Description: Request Validation has detected a potentially dangerous client input value, and processing of the request has been aborted. This value may indicate an attempt to compromise the security of your application, such as a cross-site scripting attack. You can disable request validation by setting validateRequest=false in the Page directive or in the configuration section. However, it is strongly recommended that your application explicitly check all inputs in this case.
Exception Details: System.Web.HttpRequestValidationException: A potentially dangerous Request.QueryString value was detected from the client ...
See A potentially dangerous Request.Form value was detected from the client ... for details.
Part VII: Troubleshooting Applications
Application Runs But No Data is Displayed