Originally Posted by patchymama
I am having the same problem, here is what I get from the debug command
I assume (possibly incorrectly) that the problem stems from the fact that my library was located on a portable USB drive that somehow got unplugged and renamed. it used to be "Q" and now its "R". I thought that if I uninstalled and then reinstalled the new version it would fix it, but it hasnt.
start calibre from a terminal as
calibre --with-library r:\whatever