15 Jul
This issue is marked as solved
I have a problem with my website out of nowhere I get an HTTP ERROR 500 error, checking my error_log I found several error lines like this

[14-Jul-2020 2357 UTC] PHP Parse error: syntax error, unexpected '?' in /home/dzmcroex/ on line 1085

When changing my plugin symposium.php to symposium.old, to test if it was the plugin I was correct my website works again

Please help
Shade 15 Jul Edited
Symposium requires PHP 7.1+, which allows the "??" operator. Upgrade your PHP version to solve.
Jisso 15 Jul
Solved, thank you