Invalid postback or callback argument. Event validation is enabled using ''

Question

I am getting the following error when I post back a page from the client-side. I have JavaScript code that modifies an asp:ListBox on the client side.

How do we fix

Answer 1

I know that this is a super-old post. Assuming that you are calling into your application, here is an idea that has worked for me:

1. Implement the ICallbackEventHandler on your page
2. Call ClientScriptManager.GetCallbackEventReference to call your server side code
3. As the error message states, you could then call ClientScriptManager.RegisterForEventValidation

If you don't need total control, you could use an update panel which would do this for you.