It was noticed[1] that the error messages for "missing parameter" errors were not including the module prefix, for example a query to action=query&list=search could complain that the "search" parameter must be set when the actual parameter name is "srsearch". This extends to the error code, which in this example is "nosearch" rather than "nosrsearch".

This is now fixed, and should be deployed to Wikimedia sites with MediaWiki 1.32.0-wmf.15 and later. See https://www.mediawiki.org/wiki/MediaWiki_1.32/Roadmap for a schedule.

If your client is checking for specific missing parameter error codes, it may need to be updated for the changed codes.

[1]: https://phabricator.wikimedia.org/T200155