[lomkiri]

Thanks again :-)

Binary is ok, but running calibre-debug -t from source (calibre-5.99.7.tar.xz) gives me another exception:

Spoiler:

% calibre-debug --version
calibre-debug (calibre 5.99.7*)
% calibre-debug -t       
Failed to import PyQt module: PyQt6.QtCore with error: No module named 'PyQt6'
Traceback (most recent call last):
  File "runpy.py", line 194, in _run_module_as_main
  File "runpy.py", line 87, in _run_code
  File "site.py", line 45, in <module>
  File "site.py", line 41, in main
  File "/data/opt/calibre-source/last/src/calibre/debug.py", line 282, in main
    ebook_edit(['ebook-edit'] + args[1:])
  File "/data/opt/calibre-source/last/src/calibre/gui_launch.py", line 119, in ebook_edit
    from calibre.gui2.tweak_book.main import main
  File "/data/opt/calibre-source/last/src/calibre/gui2/__init__.py", line 13, in <module>
    from qt.core import (
ImportError: cannot import name 'QT_VERSION' from 'qt.core' (/data/opt/calibre-source/last/src/qt/core.py)

"Save" and "Save a copy" are now both able to save even if the file is r/o