I ran across this little gem of a bug on VMWare’s Update Manger while trying to scan any of our hosts:
VMware Update Manager had an unknown failure: Check task and events
It was probably caused from our last upgrade. We upgraded from vCenter 5.1 on a Windows 2003 32-bit to 5.5 on Windows 2008 R2 (64-bit). VMWare’s supported helped me through the upgrade and it went smoothly. Until I had to use Update Manager. I couldn’t find anything online to help fix it so I ended up uninstalling Update Manager, re-installing it, and this time choosing to go with a blank database. Luckily, our environment is small enough that I can get away with that.