I have a really old version of Omeka, 2.4, and it does not seem to run on PHP 8. Does anyone foresee issues with me upgrading from this old version to the latest?
Not really. But it would be a good idea to test it in a secure environment/sandbox first, if possible.
Yeah, you are able to upgrade from that far back (and further) in a single step. Certainly as always make sure you have backups and so on before proceeding.
Gee, it worked! Version 2.4 on PHP 7.4 → Version 3.1 on PHP 8. Flawless.