The second time I'm involved in a large ASP.NET web project with a web farm and load balancing with no afinity (no sticky sessions), and the second time we're experiencing problems with viewstate errors :(
Again, I had to go through the code and look for Server.Transfers, identical machine keys etc. all according to the KB articles regarding this problem. But everything looks OK in the code! Things work perfect on a single box, and even on the load balanced testing machines, which has exactly the same configuration, hardware etc. I hate these problems! I heard somewhere that the viewstate problems could happen when the ASP.NET pages were compiled at different times, so what we did yesterday was to remove all temporary compiled ASP.NET files and touched the machine.config files at the same time. Now things seems to run fine.
The first time we had a few problems with the case sensitive Server.Transfers, and we upgraded to .NET Framework 1.1 and problems were solved. This application I'm talking about is still running on version 1.0 and we cannot yet upgrade it to 1.1 until it's been fully tested and so on... I'm not sure it will help, but it looks like Microsoft fixed more than a few viewstate errors from version 1.0. Tried once to disable the viewstate MAC checking, other strange things started to happen then, like form posts that didn't generate postbacks... *yikes*
Does anyone have any experience to share? The application consists of a large number of ASP.NET pages and quite many assemblies.