Background context: When changing the language links for Main Page, we don't see any wikidata recentchange injection on the subscribed clients.
Looking in udp2log logs arriving in /srv/mw-log on mwlog.svc.deployment-prep.eqiad1.wikimedia.cloud, we can see that the change propagation jobs begin as expected.
Problem: A wikidata client job crashes due to what looks like an inconsistent mix of code versions, calling a 10-parameter constructor with 8 parameters. Both sides of this code were changed in fbec9bc3edd363d0abbd407dc7e9e2fe43055676 and the deployed code on the job runner matches the new version. For some reason, the job emits an error as if the calling side of the code is at an older revision:
/srv/mw-log/exception.log:2026-09-21 06:40:39.230302 [004ed7c5-8b07-445f-bf16-5de215b3a7ed] deployment-jobrunner06 dewiki 1.47.0-alpha exception ERROR: [004ed7c5-8b07-445f-bf16-5de215b3a7ed] /rpc/RunSingleJob.php ArgumentCountError: Too few arguments to function Wikibase\Client\Changes\ChangeHandler::__construct(), 8 passed in /srv/mediawiki/php-master/extensions/Wikibase/client/WikibaseClient.ServiceWiring.php on line 191 and exactly 10 expected {"exception_url":"/rpc/RunSingleJob.php","reqId":"004ed7c5-8b07-445f-bf16-5de215b3a7ed","caught_by":"mwe_handler"}File modification timestamp precedes the logline...
-rw-r--r-- 1 mwdeploy mwdeploy 44472 Sep 19 09:01 /srv/mediawiki/php-master/extensions/Wikibase/client/WikibaseClient.ServiceWiring.php
I'm able to consistently trigger the error, even after verifying the code at this path on the jobrunner is up to date.