Mediawiki issue installing Extension:DiscussionTools

[DougInAMug]

I wrote a guide for installing Mediawiki on Uberspace some months ago https://lab.uberspace.de/guide_mediawiki/ Mediawiki is a very extendable system, and I ran into an issue installing the extension DiscussionTools on Uberspace, which is now standard on almost all Wikipedias and critical for users to have sane discussions.

After testing several different versions of Mediawiki, I wrote a bug report https://phabricator.wikimedia.org/T380885 to which I was requested to contact my service provider. I installed the extension on our 'production' server and it was issue free. Can anyone see how to fix this on Uberspace?