Update 4/7/2016: Same issue with KB3159706.
After installing the latest Windows updates, WSUS Update Services MMC console gave me a nice ‘Error: Unexpected Error’ message. Removing and reconnecting the server in MMC, didn’t help. Neither restarting ‘WSUS Service’ nor rebooting the server solved the problem. According to this article Windows update KB3148812, which recently was released, broke Windows Server Update Services (WSUS). Uninstalling this specific update and rebooting the server fixed the problem.