Error : /ScriptResource.axd : Invalid viewstate.
This issue is caused when the ScriptResource.axd querystring parameters can not be decoded on the server. This error can be caused from multiple issues with server configuration or the Browser's interaction with the server. The ScriptResource.axd contains all of the clientside javascript routines for Ajax. Just because you include a scriptmanager that loads a script file it will never appear as a ScriptResource.AXD - instead it will be merely passed as the .js file you send if you reference a external script file. In other words it is what the Microsoft Ajax libraries inject into your HTML to allow them to access their javascript functions they need for page manipulation. ASP.NET will use the machine key to encrypt the ScriptResource.axd (and webresource.axd) url's parameters(in querystring), and by default the machinekey is a randomly generated one which may involve the current time. By default there is a different machinekey on every machine, and it changes when the applic...