Log in as admin Navigate to Plugins > Manage activities in site administration Uninstall the Book module Press Continue on the confirmation page Pause when you see the following message: All data associated with the plugin mod_book has been deleted from the database. To prevent the plugin re-installing itself, its folder /var/www/html/mod/book must be manually removed from your server now. Moodle itself cannot remove the folder due to write permissions. Open DB editor Confirm that the following tables have been removed from the database: mdl_book mdl_book_chapters Back in Moodle, press Continue and allow the Book module to re-install itself Note: If this does not happen because the web server actually was able to delete the book folder, just run " git reset --hard " to restore the book folder. Then proceed to reinstall the book activity module. Manually delete the folder /var/www/html/mod/book Back in Moodle, navigate to Notifications in site administration Complete the upgrade step related to missing Book module Navigate to Plugins > Manage activities in site administration Uninstall the Book module Press Continue on the confirmation page Uninstall the book (Missing from disk) module Press Continue on the confirmation page Open DB editor Confirm that the following tables have been removed from the database: mdl_book mdl_book_chapters Note 2: At the end of the test, make sure to reset your Moodle instance's codebase (e.g. via " git reset --hard ")