Which instruction did you follow? I just realized if it's the dev instructions I forgot to include that composer install needs to be run.

I added a step on using Composer to download the PHP dependencies (if that is what the problem is): https://www.mediawiki.org/wiki/Docker/Hub#Using_for_MediaWiki_Development

I followed the docker hub install method which is the "Using on a single web server" method, also sort of related mediawiki log errors don't/won't propagate out from the container (even when setting logfile to /dev/stdout) making debugging this really really hard

In T234765#5554309, @Nwmcsween wrote:

I followed the docker hub install method which is the "Using on a single web server" method, also sort of related mediawiki log errors don't/won't propagate out from the container (even when setting logfile to /dev/stdout) making debugging this really really hard

You should see the Apache log by doing docker-compose logs -f --tail 100 (though I'm not sure how helpful that would be).

You might also enable error reporting so the errors show up on the page: https://www.mediawiki.org/wiki/Manual:How_to_debug

I'm assuming you ran through the install process and let MediaWiki setup the database?

It probably was the php composer thing as the docker hub image didn't
explain that. I cannot test it now as I used wiki.js instead.