All else in our website works, except the page that we have the post grid plug-in working. When we summon that page we have HTML Error 500. It used to work just fine, I really don't understand why this happenned all of a sudden. Posts are also fine, we can reach and view them with no problem. I tried:
1) Updating all plug-ins, themes and WordPress to their final versions
2) Creating another post grid and try to generate a preview, but it did not work either.
3) Running WP-Optimize to optimize DB tables, drafts, revisions etc.
Also this may be relevant: I started having a "A critial error occured" message when I try to reach the Posts section in the Dashboard, but I can reach my posts eventually (this happens may be once in 4 or 5 attempts).
Any other suggestions?
Main page of the website: https://www.bahaitr.org
Page with Post Grid: https://bahaitr.org/uluslararasi-haberler
Example post page: https://bahaitr.org/hz-abdulbahanin-makaminin-insaat-alanindaki-calismalar-hiz-kesmeden-devam-ediyor/