ASP.NET: Unable to validate data

Question

What is the cause of this exception in ASP.NET? Obviously it is a viewstate exception, but I can\'t reproduce the error on the page that is throwing the exception (a simple

Answer 1

I got this error when I had a form tag setup on my page without an action attribute, and then in the code-behind, I changed the form's action attribute to "Action.aspx".

And in JavaScript, I submitted the form (theForm.submit();)

I think in my case it was a security issue, and that you can't change this after it's already been set on the page... ?

Answer 2

I've experienced the issue with certain specific versions of Safari 3. My solution was to move the ViewState to the top of the form (extended the Page class and overwrote the Render method for pre-3.5 SP1, or .Net 3.5 SP1 and later does this by default), and to split up the ViewState to several different fields instead of one monster file. See ViewState Chunking in ASP.NET 2.0 (maxPageStateFieldLength)