I have also experienced this bug. By following this advice from jonaz/Rusty, I haven't seen the error message since:
"Ran into the same problem. Following jonaz__ solution, with the exception that I killed the trackerd and tracker-indexer processes, deleted the contents of ~/.cache/tracker and ~/.local/share/tracker/data then logged out, and logged back in. Tracker indexer posted a notification that it was starting up." https://bugs.launchpad.net/ubuntu/+source/tracker/+bug/361560/comments/18
I have also experienced this bug. By following this advice from jonaz/Rusty, I haven't seen the error message since:
"Ran into the same problem. Following jonaz__ solution, with the exception that I killed the trackerd and tracker-indexer processes, deleted the contents of ~/.cache/tracker and ~/.local/ share/tracker/ data then logged out, and logged back in. Tracker indexer posted a notification that it was starting up." https:/ /bugs.launchpad .net/ubuntu/ +source/ tracker/ +bug/361560/ comments/ 18