User filter "no joomdle user" 500 error

Good day!
I'm having the same problem with almost 24,000 moodle users. They are already in Joomla too. Everything worked fine for two years. But last month, when I tried the "Select filter..." option: the result was an "error 500".
I restarted mysql and apache services and everything worked fine again. Today, the error returned.

I'm using Joomdle 1.02, Joomla 3.6.5 and Moodle 2.9.
NOTE: For several conditions, my employee doesn't allow me to upgrade.

Hi.

I moved your post to a new topic, as other one was quite old.

As for the problem: I think it is related to having so many users, which makes PHP hit its memory limit when trying to deal with them.
I don't really have a solution for this right now, but I took a look at the code and there might be some room for improvement... although if you cannot upgrade that would not help much either.
I will move this to Feature Requests, so we can try to work on it for a future release. Then you might be able to backport the changes.
In the meantime, you can use the filter but only if you search for specific accounts, so it does not load so much data.

Antonio, thank you so much for your help!
I'll continue working as you say, looking for users one by one. And if you allow me, I'll copy a screenshot of your answer in order to justify an upgrade.

Have a nice day.

Sure, it is always good to have proof that sometimes upgrades are not evil