Error: “System.Web.Mvc.HttpAntiForgeryException (0x80004005): The anti-forgery cookie token and form field token do not match.” (206653)

While navigating the PMUser site you may get a “System error occurred. For more information, view the event log.” error. And the following a number of those entries can be found in the event log:

Result: CriticalError

Info:

System.Web.Mvc.HttpAntiForgeryException (0x80004005): The anti-forgery cookie token and form field token do not match.

   at System.Web.Helpers.AntiXsrf.TokenValidator.ValidateTokens(HttpContextBase httpContext, IIdentity identity, AntiForgeryToken sessionToken, AntiForgeryToken fieldToken)

   at System.Web.Helpers.AntiXsrf.AntiForgeryWorker.Validate(HttpContextBase httpContext)

   at System.Web.Mvc.ControllerActionInvoker.InvokeAuthorizationFilters(ControllerContext controllerContext, IList`1 filters, ActionDescriptor actionDescriptor)

   at System.Web.Mvc.Async.AsyncControllerActionInvoker.<>c__DisplayClass25.b__1e(AsyncCallback asyncCallback, Object asyncState)

This is likely related your load balancing solution (i.e. F5). Requests are being sent from the same session to a different PM server and therefore causing the error. 

SOLUTION

Resolution 1

You’ll need to enable some form of session persistence to make sure that requests from the same IP or from the same User goes to the same PM server.

Check the documentation that comes with your load balancer for details on how to configure session persistence.

Resolution 2

Generate Machine Keys:

https://blogs.msdn.microsoft.com/vijaysk/2009/05/13/iis-7-tip-10-you-can-generate-machine-keys-from-the-iis-manager/

The machine keys should be placed inside the section of the web.config file as suggested Microsoft.

https://msdn.microsoft.com/en-us/library/w8h3skw9%28v=vs.85%29.aspx?f=255&MSPPError=-2147217396