List of Issues Experienced with SharePoint January 2018 CU

At one particular client site, after we applied the January 2018 CU to their SharePoint 2013 environment, we found that one site column, which was used in multiple site collections, all of a sudden had a space in its internal name (which is not valid). For the end user, this was preventing them from creating new Document Sets within a library. What I found was that even though the offending field wasn't in the Document Set Content Type that they were trying the use, the fact that the invalid field was associated with the list (via another content type), during the process of creating the document set it throws an internal error "The schema for field with this name is wrong or missing. Field 'Meeting Type'".  As the Document Set errors were not discovered until several days after the patch was applied, we could not roll back to the snapshot taken prior to the CU being applied. To fix the issue (as we didn't want to wait for Microsoft Support), we created a new field, added it to the Content Type, removed the offending field, then had to go into every library and physically remove the old field from there also.

Another issue we experienced with the Jan 201 CU was that also SharePoint thought the User Profile Sync service was started, under the covers in the Services.msc snap-in, it was not (even though it was set to Automatic). The underlying error in the Event log was 'Detection of product '', feature 'PeopleILM' failed during request for component ''. This was due to the Network Service not having access to the C:\Program Files\Microsoft Office Servers\15.0\SQL\DatabaseSetttings.sql file. By giving the Network Service account read/execute rights to the 15 folder, the Synchronization service was able to be started and we were able to do profile imports again.

Note that for another customer, were I had setup a SharePoint/Project Server 2016 environment, the January 2018 CU ships with a corrupt resource file 'PWA.en-us.resx', which prevents you from administering projects (i.e. all action buttons in the ribbon are disabled). To fix this, we overwrote the file with a copy of the PWA.resx file.