From ArchWiki

API problems

This emacs extension does open the Arch wiki but it is incapable of saving the changes. There seems to be an API problem, but I don't understand Elisp nor the media wiki API to debug this. —This unsigned comment is by Titan-c (talk) 17:36, 2 September 2017‎ (UTC). Please sign your posts with ~~~~!

Yup, same here, I haven't properly investigated, but maintenance has been on the low in recent years, it is a tad broken nowadays. --Ambrevar (talk) 18:04, 2 September 2017 (UTC)