Hi Leon thanks for your reply, my previous version is 3.11+
and I upgraded to 3.11.1, I always try to stay on the latest version, normally I do this with every new version.
This time I did nothing different. If I'm not mistaken, I received an email about the new version warning on July 12, I took a backup of my current site at 12 at night, I deleted the files in the moodle main directory (I did not touch the moodledata folder)
Then I removed the new files and the upgrade was successful, I am a trainee who registered before the upgrade today, the course it said it couldn't see the assignment, and when I checked it booom... 500 students enrolled in the course were not in the registered users link.
I immediately went to the site administration, I wonder if the users were deleted, no, they were standing still. only course assignments have been deleted. These users are registered manually (with csv), I do not use a plugin for user registration.
When I restored the database
to a backup from a few days ago, my students in the course started to appear as registered, I wonder in which table these course records are kept, if I just restore them, my problem seems to be fixed for now.
now it is upgrading the database again, let's see if my users whose course registrations have just been deleted will delete their course registrations again.
Upgrading Moodle database from version 3.11+ (Build: 20210520) (2021051700.01) to version 3.11.1 (Build: 20210712) (2021051701.00)
yes, it has upgraded the database and my users seem to be registered in the course again. If I can manage to restore this table, I think my problem will be completely gone.