Hey there!

We are using Redis for sessions & app/session cache storing. However, we have recently noticed that our Redis was getting filled up over time and for no apparent reason. The biggest contributor to this was the session cache.

After some digging, I've noticed, that the \core\task\cache_cron_task task (that to my understanding cleans up old session cache data) throws these warnings:

foreach() argument must be of type array|object, bool given, in /var/www/moodle/cache/classes/helper.php, line 743

Would it be possible to fix this bug even if 3.11 isn't supported anymore? I suppose it could be backported...

We are using the latest PHP 8.0 with redis 5.0.7.