[ownedbycats]

The current Kobo firmware has a glitch where the database doesn't always close itself properly when connecting to the computer. This most commonly happens when connecting with a KePub open but there's other circumstances.

If you don't have a backup made with Kobo Utilities, sign out and sign back in. This will reset the database and fix it. You'll lose all your reading positions and annotations. Sideloaded books will re-import into the newly initialized database.

Rebooting the device before connecting to PC usually prevents it. It's also suggested to use Kobo Utilities to keep backups.