[lewisdale]

I installed Calibre 5.12 on Debian using apt install but Calibre won't start. I frankly don't understand the traceback shown below.

calibre --ignore-plugins
Traceback (most recent call last):
File "/usr/bin/calibre", line 19, in <module>
from calibre.gui_launch import calibre
File "/usr/lib/calibre/calibre/__init__.py", line 23, in <module>
initialize_calibre()
File "/usr/lib/calibre/calibre/startup.py", line 104, in initialize_calibre
set_translators()
File "/usr/lib/calibre/calibre/utils/localization.py", line 268, in set_translators
lang = get_lang()
File "/usr/lib/calibre/calibre/utils/localization.py", line 90, in get_lang
from calibre.utils.config_base import prefs
File "/usr/lib/calibre/calibre/utils/config_base.py", line 13, in <module>
from calibre.utils.lock import ExclusiveFile
File "/usr/lib/calibre/calibre/utils/lock.py", line 16, in <module>
from calibre_extensions import speedup
ImportError: cannot import name 'speedup' from 'calibre_extensions' (unknown location)

What is Calibre trying to tell me?