This task is about MediaWiki's core codebase.
One of the errors that people run into when setting up new MediaWiki installations is
"Could not open lock file for "mwstore://local-backend/local-public/..."
(in English; the message ID is lockmanager-fail-openlock).
That message is unhelpful and should be descriptive/helpful for fixing the problem.
It should be changed to something like this:
"Could not open lock file for "mwstore://local-backend/local-public/...". Make sure your upload directory is configured correctly and your web server has permission to write to that directory. See https://www.mediawiki.org/wiki/Special:MyLanguage/Manual:$wgUploadDirectory for more information."
You are expected to provide a patch in Wikimedia Gerrit. See https://www.mediawiki.org/wiki/Gerrit/Tutorial for how to set up Git and Gerrit.