Comment 22 for bug 872639

I had the exact same problem. As suggested by Mike I looked at the page http://www.freedesktop.org/wiki/Specifications/desktopcouch/Documentation/Troubleshooting

This page has a section called "Killing and restarting desktopcouch". I decided to follow these instructions. In step 1 and 2 the desktopcouch process is killed and desktop-couchdb.ini is removed. In step 3 the desktopcouch should be restarted. In my case, however, this process could not be started. At that point I decided to restart the machine. (I'm not sure I this is a required step) After restarting the machine and starting Thunderbird the error did not return. This seems to have fixed the problem.