I get the error whenever I try to sync from shelf. Any of the exclusive shelves. I haven't had a problem with this in the past. I know that when I go to add, there is a book limit, but not with the sync from shelf. I have had no problems downloading tags. I think it happened when I started to add commands to the sync from shelf. I wanted to add a "date added" with the date formatted, a yes/no, and a new tag. I went back and redid the set up and put it back with the tags only, and now it works. The following is from my "to read" shelf that I haven't set back to the original way it was set up.
calibre, version 2.46.0
ERROR: Goodreads Failure: The request contacting Goodreads has failed. Please try again.
URL:
http://www.goodreads.com/review/list...1&per_page=200
Response Code: 401
not authorized