Forum Discussion
Error after Update to CU5 (6.0.9319.281)
It seems that you have forgotten to apply the update to the SQL databases.
Follow the "To apply the update to a back end server or Standard Edition server" instructions from the "https://support.microsoft.com/en-us/help/3061064/updates-for-skype-for-business-server-2015" article and the EventID 57005 and 57006 will not appear again.
The point is, first you have to Update all the FrontEnd Server bevor you Update the Backend. Like it's written in the article https://support.microsoft.com/en-us/help/3061064/updates-for-skype-for-business-server-2015.
For me, I stopped after the Error was shown on the first FrontEnd Server. I wanted to make sure that there was no other problem, like this one: https://itbasedtelco.wordpress.com/2017/05/17/warning-may2017-windows-update-may-break-skype-for-business-2015-server/
When I have time, I will update all the Server and the Backend.