[midol]

For no apparent reason I'm now getting this error when starting calibre on my Mint 20 laptop, does anyone know why?

dave@dave-900X1B:~$ calibre
qt5ct: using qt5ct plugin
Traceback (most recent call last):
File "/usr/bin/calibre", line 20, in <module>
sys.exit(calibre())
File "/usr/lib/calibre/calibre/gui_launch.py", line 73, in calibre
main(args)
File "/usr/lib/calibre/calibre/gui2/main.py", line 543, in main
listener = create_listener()
File "/usr/lib/calibre/calibre/gui2/main.py", line 514, in create_listener
return Listener(address=gui_socket_address())
File "/usr/lib/calibre/calibre/utils/ipc/server.py", line 110, in __init__
self._listener._unlink.cancel()
AttributeError: 'NoneType' object has no attribute 'cancel'
Error in sys.excepthook:
Traceback (most recent call last):
File "/usr/lib/python3/dist-packages/apport_python_hook.py", line 153, in apport_excepthook
with os.fdopen(os.open(pr_filename,
FileNotFoundError: [Errno 2] No such file or directory: '/var/crash/_usr_bin_calibre.1000.crash'

Original exception was:
Traceback (most recent call last):
File "/usr/bin/calibre", line 20, in <module>
sys.exit(calibre())
File "/usr/lib/calibre/calibre/gui_launch.py", line 73, in calibre
main(args)
File "/usr/lib/calibre/calibre/gui2/main.py", line 543, in main
listener = create_listener()
File "/usr/lib/calibre/calibre/gui2/main.py", line 514, in create_listener
return Listener(address=gui_socket_address())
File "/usr/lib/calibre/calibre/utils/ipc/server.py", line 110, in __init__
self._listener._unlink.cancel()
AttributeError: 'NoneType' object has no attribute 'cancel'
dave@dave-900X1B:~$ uname -a
Linux dave-900X1B 5.4.0-52-generic #57-Ubuntu SMP Thu Oct 15 10:57:00 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux
dave@dave-900X1B:~$