I am hesitant to say that I have good news or that I have fixed anything...
I honestly don't know if there is anyone left still using this site after all the problems we've had.
That said, I noticed that there were some very recent (as in yesterday/today) commits to the development branch of kbin that look like they address the issues that fedia has been experiencing. I moved fedia to the development branch and reloaded some things, and so far, no error 500's.
But, caveat emptor, we are on the development branch of early-in-its-lifecycle open source software.
@jerry I think it might be all posts from 196@lemmy.blahaj.zone. Checked on kbin.social, works fine, but on Fedia I get a 500 error when visiting the magazine.
ETA: I also get a 500 error when trying to message a user from a different instance, even on the same platform (fedia.io -> kbin.social). This seems to be a platform bug, as trying to message this account from my kbin.social one results in me getting sent to home.
I'm now getting a 500 on https://fedia.io/all and on https://fedia.io/mod/microblogMy subs (where I've been spending most of my time), and the main microblog feed are working fine. Odd.
Edit: my personal subs list page seems to be doing this too: https://fedia.io/settings/subscriptions/magazines