PHP Warning: Encountered a UnresolvedRedirectException when trying to load Q60778842 [Called from Wikibase\Client\DataAccess\Scribunto\EntityAccessor::getEntity in /srv/mediawiki/php-1.33.0-wmf.16/extensions/Wikibase/client/includes/DataAccess/Scribunto/EntityAccessor.php at line 153]
Reproduction path: call get entity data lua function on ID of an Item which is a redirect to an Item which is also a redirect (i.e. two redirects).
Impact
This is causing a fatal error during the rendering of pages, which can abort edits from being saved, and existing pages from being rendered.
Analysis
So this is an issue with double redirects.
The behaviour that is done in Mediawiki for wikitext pages is demonstrated at https://test.wikidata.org/wiki/Wikidata:RedirectInclusion== Redirect 1 == {{Wikidata:Redirect1}} == Redirect 2 == {{Wikidata:Redirect2}} == Target == {{Wikidata:RedirectTarget}}Here we see a fallback to something dumb in the double redirect case
Right now in wikidata for LUA inclusion this results in errors.We could:
- Provide blank data in cases like this (it would come back when the double redirect is fixed)
- Follow 1 more layer of redirects (would move the issue to if there triple redirects instead then, less common)
- Stop wikibase from ever allowing double redirects in any situation?
Product decision:
Acceptance Criteria
- Double redirects no longer cause fatal errors when accessing data through them in LUA
- When this sort of data access happens, no data is returned by Wikibase
- When this sort of data access happens no log messages are created (as this is expected behaviour)
Notes on expected state:
As well as the ACs listed above bots and users would continue to operate on wikidata and affected wikibases to remove these double redirects.
This ticket is only about stopping the logs and exceptions in this situation.