After publishing a new build of my ASP.NET MVC web application, I often see this exception thrown when browsing to the site:
System.Web.Mvc.HttpAntiForgeryException: A required anti-forgery token was not supplied or was invalid. ---> System.Web.HttpException: Validation of viewstate MAC failed. If this application is hosted by a Web Farm or cluster, ensure that configuration specifies the same validationKey and validation algorithm. AutoGenerate cannot be used in a cluster. ---> System.Web.UI.ViewStateException: Invalid viewstate.
This exception will continue to occur on each page I visit in my web application until I close out of Firefox. After reopening Firefox, the site works perfectly. Any idea what's going on?
Additional notes:
- I am not using any ASP.NET web controls (there are no instances of runat="server" in my application)
- If I take out the <%= Html.AntiForgeryToken %> from my pages, this problem seems to go away