[Mister L]

Thank you davidfor for this answer. I tried doing what you suggested (disclaimer: I have never worked with SQLite databases before). I installed SQLite tools (https://www.sqlite.org/download.html) and followed instructions on this page
https://www.sqlitetutorial.net/download-install-sqlite/

The first command seems to have worked, the second gave me an error message :

Spoiler:

sqlite> .cd H:\.kobo
sqlite> .open KoboReader.sqlite
sqlite> REINDEX content_bookid_index;
sqlite> REINDEX sqlite_autoindex_content_1;
Error: stepping, UNIQUE constraint failed: content.ContentID (19)
sqlite>

After running these commands I again launched Calibre but I get the same errors.

When attempting to save the database at connection:

Spoiler:

calibre, version 5.24.0 (win32, embedded-python: True)
Echec à la sauvegarde de la base de données du dispositif: Échoué: Sauvegarde de la base de données du dispositif Kobo en cours


*** in database main ***
On tree page 56787 cell 0: Rowid 103877 out of order
row 81795 missing from index content_bookid_index
wrong # of entries in index sqlite_autoindex_content_1

Traceback (most recent call last):
File "calibre\gui2\device.py", line 89, in run
File "calibre_plugins.koboutilities.jobs", line 200, in do_device_database_backup
Exception:
*** in database main ***
On tree page 56787 cell 0: Rowid 103877 out of order
row 81795 missing from index content_bookid_index
wrong # of entries in index sqlite_autoindex_content_1

Check database:

Spoiler:

Résultat de l'exécution de la commande 'PRAGMA integrity_check' sur la base de données du dispositif Kobo:


*** in database main ***
On tree page 56787 cell 0: Rowid 103877 out of order
row 81795 missing from index content_bookid_index
wrong # of entries in index sqlite_autoindex_content_1

Is there something obvious I've done wrong?