Hello,
The deployment of MediaWiki 1.26wmf18 (starting on August 11) will no longer include the legacy and deprecated sajax JavaScript library. It has been emitting deprecation warnings since June 2013[1] (1.22).
Reedy has helpfully provided a list of affected site and user scripts on public Wikimedia wikis on Phabricator[2]. Details on how to migrate are provided at [3] (it should be simple to run a semi-auto find/replace bot with a few regexes).
If you run into issues migrating or need help, feel free to ask on wikitech-l, IRC (#wikimedia-tech) or m:Tech[4].
[1] https://phabricator.wikimedia.org/rMW35b6b63e48b91c718dd07fa2383104060149b27... [2] https://phabricator.wikimedia.org/T55120#1514868 [3] https://phabricator.wikimedia.org/T55120#1514898 [4] https://meta.wikimedia.org/wiki/Tech
Thanks, -- Legoktm