So you have upgraded a web application from .NET 2.0 to .NET 4.0 or higher and now you are getting errors that say there is a potentially dangerous request.:
And you specifically allow <> tags in your control by setting the ValidateRequest=”false” on the page? Well this would be because a change in .NET 4.0 makes it so this settings isn’t enough. Now you have to add the following to the web.config to revert Request Validation back to 2.0:
Remember not to duplicate your tags. If you want to do this just for a specific page you can also do this:
Remember though, that if you disable Request Validation, you should have some other means programmed in to validate the incoming data.