Edit: Update Rollup 18 is now available for Exchange 2010 SP3 see the post Exchange 2010 SP3 Update Rollup 18 installation tips.
WARNING – DO NOT INSTALL THIS UPDATE IF YOU DOWNLOADED IT ON THE 9th or 10th DECEMBER!
Yet again the testing and quality assurance process for Exchange updates has failed! Each time this happens it knocks the confidence IT professionals have in deploying Exchange updates, I’m sure with the end result being more unpatched Exchange Servers in the wild.
Microsoft I think you need to up your game here, get the Exchange quality assurance process in order and don’t release any more Update Rollups or Patches which break things.
As ever, if you have seen my previous articles on installing Update Rollups don’t ever install them on release day in production, wait at least a couple of weeks just in case something like this happens!