The problem i two-fold :
1) from the error-page posted, it seems as if the forum is still running on MySQL 4.
MySQL 4 is EOL a loooong tiem ago & doesn't even turn up in the official eol notices any longer :
https://endoflife.software/applications/databases/mysql2) when creating a Mysql db table, one has to assign a text-encoding to it. If this isn't one of the ut8-variants, you get these types of crash.
3) when looking at the server headers, I see : X-Powered-By: PHP/5.6.36-pl0-gentoo ; so we've also got a seriously outdated and eol'ed version of php.
The correct course of action is :
1) export the databases
2) upgrade the whole server (it's a gentoo version). how to do that is described here :
https://wiki.gentoo.org/wiki/Upgrading_Gentoo3) alter the dbs to correctly support utf8 :
https://www.monolune.com/mysql-utf8-cha ... explained/https://www.a2hosting.com/kb/developer- ... base-utf-8