Calibre crashes on startup

[Stefano Dall'Agata]

I can't start Calibre anymore

$ lsb_release -rd
Description: Ubuntu 20.04.1 LTS
Release: 20.04

~$ apt-cache policy calibre
calibre:
  Installato: 4.99.4+dfsg+really4.12.0-1build1
  Candidato: 4.99.4+dfsg+really4.12.0-1build1
  Tabella versione:
 *** 4.99.4+dfsg+really4.12.0-1build1 500
        500 http://it.archive.ubuntu.com/ubuntu focal/universe amd64 Packages
        500 http://it.archive.ubuntu.com/ubuntu focal/universe i386 Packages
        100 /var/lib/dpkg/status

I expected to open the program normally

The program crashes

This is what if I boot from terminal:

~$ calibre
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'

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: calibre 4.99.4+dfsg+really4.12.0-1build1
ProcVersionSignature: Ubuntu 5.4.0-58.64-generic 5.4.73
Uname: Linux 5.4.0-58-generic x86_64
ApportVersion: 2.20.11-0ubuntu27.14
Architecture: amd64
CasperMD5CheckResult: skip
CurrentDesktop: Unity:Unity7:ubuntu
Date: Fri Dec 25 10:23:54 2020
InstallationDate: Installed on 2020-05-17 (221 days ago)
InstallationMedia: Ubuntu 20.04 LTS "Focal Fossa" - Release amd64 (20200423)
PackageArchitecture: all
SourcePackage: calibre
UpgradeStatus: No upgrade log present (probably fresh install)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.