I have a 2 node web farm for testing (replicating my production environment). Now, after I install VS2010 on one of the nodes (one of the nodes doubles as a build server), it would seem as if the machine keys got desynched.
If I access my app on each node all works fine (from localhost, and taking the other node off the farm), but when I have both nodes in the array, I get http errors (500, 404s and 401s) on several of the page resources (I suspect the ones that get routed to the server that did not created the auth cookie), and I also get a bunch of "Length of the data to decrypt is invalid" exceptions. These leads me to believe the auth cookie generated by a server is not compatible with the other server and thus the machineKeys on the two nodes are different, but I can't figure out where!.
Some more info:
The machineKeys are specified in my apps web.config and are the same on both, and both have SHA1 algo
Both apps are running .net 2.0 framework (asp.net 3.5 apps) with the same configuration in the pool.
Both servers are running w2k3 server with all updates installed, except that one of the servers has .net4.0 and VS2010 installed and the other does not.
None of the servers have a machine key specified in the global machine.config, so they should be using the web.config ones, right?
Any ideas on where to look next?