What a crazy error.
There are a few posts about this but very little that tell you what is going on. When you attempt to upgrade the farm with the following command (after applying a public update or even after the 2016 upgrade):
PSConfig.exe -cmd upgrade -inplace b2b -wait -force -cmd applicationcontent -install -cmd installfeatures -cmd secureresources
You could get the above error in one of the final upgrade stepsactions. Psconfig.exe is attempting to upgrade all your service application and content databases to your current binary level. This particular error will show up if someone in your organization was "smart" enough to decided to make a content database a project server database. You will see this by looking at the tables in the database. If you see any that are related to Project Server, then you know someone did something really dumb.
You can get your farm to upgrade by simple removing the offending database (aka detach it), then run the command to upgrade everything else.
Resolution would be to remove all the project server based tables (make a backup of course) and then try your upgrade again. You could also attempt to tell SharePoint that the database is a "Project Server" database and attempt to upgrade it via Project Server but no guarantee that will work especially if the databases are from 2007/2010 days. You would need a Project Server environment to upgrade all the way from the old version to the latest.
Enjoy,
Chris