Keeping your servers up to date is essential, and not only the application server parts but the OS and others as well. The other day I went with a Windows Update that also included a Lync Server security update. After a short while I would get feedback from users no longer being able to use the mobile client, and later I also got reports on the Web App not working.
Normally I would run all my Lync updates using the standalone LyncServerUpdateInstaller.exe to better keep track of dependencies and such, but as there was no new CU for Lync (since July) I decided to update Lync with Microsoft’s recommended security patch nevertheless.
After getting the first reports I would dive into Event Manager to see what errors were being reported. I quickly noted that the newly updated Web Components service was the one to blame.
The error clearly points to some components missing or not being installed properly. I first decided to uninstall the KB and that fixed the problem with the mobile client.
The Web App would, however, still not work properly – the user would log in (no longer the “something went wrong” message) but there would be no content available.
Thinking that there would still be some dependencies on the now uninstalled patch I tried reinstalling it. This time I also checked out not only the “Important updates” but also the “Recommended updates” section. Turns out that the important security KB comes with a dependant “recommended” KB as well that will update Core Components.
Solution: Make sure to install KB3080356 along with the important Security KB3080353 when using Windows Update. Server restart required.
Note: I have not tried to install the KB using the standalone LyncServerUpdateInstaller, the optional KB might be included there.