Sometimes I receive the following error: Validation of viewstate MAC failed. If this application is hosted by a Web Farm or cluster, ensure that <machineKey> configuration specifies the same validationKey and validation algorithm. AutoGenerate cannot be used in a cluster. What could it be?
http://community.discountasp.net/showthread.php?t=2719 http://community.discountasp.net/showthread.php?t=9605 http://community.discountasp.net/showthread.php?t=11140 Discussed many times in this forum. And solved.