[MaxG]

I installed Calibre after upgrading to Mint 20; worked like a charm

Now, a few months later I was going to use it again, and it failed to launch.

running calibre in debug mode revealed the following:

calibre-debug -g
calibre 4.99.4  embedded-python: False is64bit: True
Linux-5.4.0-47-generic-x86_64-with-glibc2.29 Linux ('64bit', 'ELF')
('Linux', '5.4.0-47-generic', '#51-Ubuntu SMP Fri Sep 4 19:50:52 UTC 2020')
Python 3.8.2
Interface language: None
Traceback (most recent call last):
  File "/usr/bin/calibre-debug", line 20, in <module>
    sys.exit(main())
  File "/usr/lib/calibre/calibre/debug.py", line 277, in main
    calibre(['calibre'] + args[1:])
  File "/usr/lib/calibre/calibre/gui_launch.py", line 73, in calibre
    main(args)
  File "/usr/lib/calibre/calibre/gui2/main.py", line 529, in main
    app, opts, args = init_qt(args)
  File "/usr/lib/calibre/calibre/gui2/main.py", line 114, in init_qt
    app = Application(args, override_program_name=override, windows_app_uid=MAIN_APP_UID)
  File "/usr/lib/calibre/calibre/gui2/__init__.py", line 875, in __init__
    raise RuntimeError('Failed to load the progress_indicator C extension, with error: {}'.format(pi_err))
RuntimeError: Failed to load the progress_indicator C extension, with error: PyCapsule_GetPointer called with incorrect name
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-debug.1000.crash'

Original exception was:
Traceback (most recent call last):
  File "/usr/bin/calibre-debug", line 20, in <module>
    sys.exit(main())
  File "/usr/lib/calibre/calibre/debug.py", line 277, in main
    calibre(['calibre'] + args[1:])
  File "/usr/lib/calibre/calibre/gui_launch.py", line 73, in calibre
    main(args)
  File "/usr/lib/calibre/calibre/gui2/main.py", line 529, in main
    app, opts, args = init_qt(args)
  File "/usr/lib/calibre/calibre/gui2/main.py", line 114, in init_qt
    app = Application(args, override_program_name=override, windows_app_uid=MAIN_APP_UID)
  File "/usr/lib/calibre/calibre/gui2/__init__.py", line 875, in __init__
    raise RuntimeError('Failed to load the progress_indicator C extension, with error: {}'.format(pi_err))
RuntimeError: Failed to load the progress_indicator C extension, with error: PyCapsule_GetPointer called with incorrect name

... however, I cannot make sense of it.

I then decided to remove calibre, and installed it again; same result.
Any hints appreciated.