This error around the web is defined as a missing document template. This is true but there is a more bizare situation in which I ran into.
According to SharePoint I had a proper document template assigned to the content type yet I got this error and it messed up my content hub workings. I could not publish updates of the content type to other locations.
The fix: I simply added a new document template to the content type, re-published to content type and it worked.