Hoping to acquire some feedback. I just updated from 2.7.3 to 3.0.5 and all seemed to go well—manager loads and the site loads. During the upgrade, there was an alert about: The sessions garbage collector does not start! What does this mean, and do I need to change a setting somewhere? Other that than and one ModMore Extra that had strange feedback during the update may need some investigation. So far so good though.
What was the exact output?
There is a warning that always gets displayed on install, even when the settings are all correct.
See also this topic:
Maybe take a look at the size of the table modx_session from time to time. Only if the size is always increasing and old entries never get deleted, you have to act.
I appreciate the feedback. the session table has 378 rows. Will have to learn more to understand the what and when of this table. Here is the full warning: The sessions garbage collector does not start! The current configuration “session.gc_probability” is set to 0 and “session.gc_divisor” is set to 0.
By default, MODX stores sessions in the database, so misconfiguration of these options can cause the session table to grow in size.
Yes these settings look bad (if you use the default MODX session handling ( → system setting session_handler_class = MODX\Revolution\modSessionHandler).
Take a look at this article or maybe this topic to learn more about how to solve the issue.
Did you use the same server (with the same settings) when your site was still on MODX 2? Because the session handling is exactly the same in MODX 2 and MODX 3 and this amount of database entries doesn’t indicate a problem with the garbage collection.
Yes. Same server… same settings—except php version updated to 7.4 I think. Merely upgraded to MODx 3.0.5 and honestly never looked at the tables. After the upgrade I did copy, then deleted all errors in the manager… mainly because a look were a result of version 2 updates, and issues with Extras. This being said… I am now seeing bad link errors pop in a few at a time. That happen to be associated with a button for which the tv link field is blank. I did find a fix that I am going to try out. It’s basically a conditional button where if I have a Photogallery for the page… the is a button to load it. I probably originally did not build it in the best way. I am paying closer attention to the errors now… and looking to give the site an overhaul, and remove components and stray code that are not used. Site was built with Foundation… 4 maybe… cannot remember now. Surprisingly has worked pretty well for a long long time… years! Time for an overhaul. Looking at Tailwind css, but also hesitant to delve into something completely different. 
One crime at a time so to speak.