Archive page and archived issues not working properly in OJS 3.4

Before setting our OJS 3.4 site to live, we did some browsing. Everything seemed fine, until we tried accessing issues older than ca 2020 in the archive. 2023, 2022 and 2021 issues are working as intended, but anything older gives us a http 500 error.

The older issues can still be edited in the admin area.

Tried both healthSceinces and standard theme. Same issue.

What could this be??

This applies to all our journals across this OJS installation. The upgrade worked fine except for some log files which had to be deleted before upgrading the database.