"Unable to validate data" HttpException from my .net 2.0 application

Question

I am getting this exception from my ASP .net application running in a webfarm.

Exception Type: System.Web.HttpException
Exception Message: Unable to validate data.

---- Stack Trace ----
 System.Web.Configuration.MachineKeySection.GetDecodedData(buf As Byte[], modifier As Byte[], start As Int32, length As Int32, dataLength As Int32&)
 (unknown file): N 00294
 System.Web.UI.ObjectStateFormatter.Deserialize(inputString As String)
 (unknown file): N 00203

I have already configured static machine key in all the servers as per this article: http://support.microsoft.com/default.aspx?scid=kb;en-us;Q312906. (All servers have the same machine key)

Any Ideas?

I wonder why no one is responding to this? Is it just me?

Answer 1

I'm not sure of the problem, but I think this is the issue, taken from this post :-

If a user stops a postback (usually by hitting the back button or stop button in the browser), not all the data is sent back to the server. When ASP.NET validates the viewstate, it fails.

I think the bug (if you can call it one) is actually in IIS, not ASP.NET. If the full postback isn't received, IIS shouldn't forward the request to ASP.NET.

Anyhow, the good news is this error doesn't affect the user's experience in any way. They navigated away from the page or stopped the postback and got exactly what they asked for. The server choked on the response, but that's exactly what it should do.

I'm not happy with this suggestion .. but I'm not sure of a better solution :( it's filling up my error logs big time :(