We have a .NET 3.5 production website running on Windows Server 2012, that has not had any code changes recently, and one of the servers on the farm started throwing this error last night:
Unable to cast object of type 'ASP.mni_master' to type 'ASP.mni_master'
This was occurring randomly on a variety of web pages that use the master page mentioned. Sometimes the page came up fine, sometimes it threw this error. We have two servers on the farm.
One was patched with the most recent Windows updates and .NET critical updates last Saturday at noon, and the other was not (we do that on purpose, just in case). The one that was patched is the one that is throwing this error, although it didn't show up
until about 11pm last night (Tuesday). This website is used heavily 24/7 so I'm not sure if it's related to the patches since more than 3 full days had passed since the pat ...
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