To fix this on Ubuntu 20.04 , 4.99.4+dfsg+really4.12.0-1build1:
sudo sed -ie 's/self._listener._unlink.cancel/# self._listener._unlink.cancel'/ /usr/lib/calibre/calibre/utils/ipc/server.py
To fix this on Ubuntu 20.04 , 4.99.4+ dfsg+really4. 12.0-1build1:
sudo sed -ie 's/self. _listener. _unlink. cancel/ # self._listener. _unlink. cancel' / /usr/lib/ calibre/ calibre/ utils/ipc/ server. py