Howard Miller

See above

The sessions table continues to record the user id and session cookie value relationship. But that's all. It no longer stores actual session data.

If you un-click the 'Use database...' option and save, Moodle will revert to saving sessions in files in the moodledata area. You don't need to do anything else. Note that everybody will be logged out when you save.

As above, if it's a busy site an even better idea is to implement Redis as a session provider. The configuration for that is not in the admin interface. The options are explained in the config-dist.php file.

Handling sessions in files is the default, so all you need to do is switch off database sessions.

As you have discovered, database sessions don't work well. I don't recommend them. A MUCH better solution is to set up a Redis server and use that for sessions, instead.

Redis sessions are configured in config.php. See Session_handling for the full story.

Mmm..... screenshot please?

 

I'm not seeing that option and I literally cannot find the language string 'Send mail'. So, I'm wondering if this is some modification / plugin. I reserve the right to be completely wrong, however