Hello, technical contributors!
The MediaWiki Interfaces team is deprecating XSLT stylesheets within the
Action API.
Support for the format=xml&*xlst={stylesheet}* will be removed from
Wikimedia projects by the end of November, 2025. In addition, it will soon
be disabled by default in MediaWiki release versions: v1.43 (LTS), v1.44,
and v1.45. Support for XSLT stylesheets will be fully removed from
MediaWiki v1.46 (expected to release between April and May 2026).
*=== Why are we deprecating and removing this capability? ===*
Support for XSLT is generally being removed from browsers, due to a high
rate of security risks and declining usage. Chrome is officially starting
the XSLT deprecation cycle
<https://developer.chrome.com/docs/web-platform/deprecating-xslt>in
November 2025, with full removal expected by November 2026. Other browsers
are expected to follow. To ensure that we are not including a feature that
will no longer be supported by browsers, we decided to end support, as
well.
*=== What is the impact? === *
There is currently very limited adoption of this feature across Wikimedia
projects, with usage limited to a handful of gadgets that currently rely on
this capability. We are engaging with some of the key gadget owners
directly, so they are aware of the change and can adjust or remove lesser
used features accordingly.
We also recognize that some third parties may rely on XSLT stylesheets. In
this case, we encourage consumers to find alternative solutions as soon as
possible, given the end of XSLT support goes beyond the scope of MediaWiki.
I encourage tool developers, gadget authors, and third party users to
engage directly if you have questions, concerns, or if this change may
block your ability to upgrade to future versions in a timely manner.
Thanks,
Halley
*Halley Coplin* (she/her)
Sr. Product Manager, MediaWiki Interfaces
Wikimedia Foundation <https://wikimediafoundation.org/>