=== Error ===
`MediaWiki version:` **`1.35.0-wmf.15`**
```name=message
Term type 'alias' is not supported
```
```name=exception.trace,lines=10
#0 /srv/mediawiki/php-1.35.0-wmf.15/extensions/WikibaseMediaInfo/src/Services/MediaInfoPrefetchingTermLookup.php(108): Wikibase\MediaInfo\Services\MediaInfoPrefetchingTermLookup->prefetchTerm(Wikibase\MediaInfo\DataModel\MediaInfoId, array, array)
#1 /srv/mediawiki/php-1.35.0-wmf.15/extensions/Wikibase/data-access/src/ByTypeDispatchingPrefetchingTermLookup.php(52): Wikibase\MediaInfo\Services\MediaInfoPrefetchingTermLookup->prefetchTerms(array, array, array)
#2 /srv/mediawiki/php-1.35.0-wmf.15/extensions/Wikibase/data-access/src/ByTypeDispatchingPrefetchingTermLookup.php(52): Wikibase\DataAccess\ByTypeDispatchingPrefetchingTermLookup->prefetchTerms(array, array, array)
#3 /srv/mediawiki/php-1.35.0-wmf.15/extensions/Wikibase/client/includes/Api/PageTerms.php(91): Wikibase\DataAccess\ByTypeDispatchingPrefetchingTermLookup->prefetchTerms(array, array, array)
#4 /srv/mediawiki/php-1.35.0-wmf.15/extensions/Wikibase/client/includes/Api/PageTerms.php(76): Wikibase\Client\Api\PageTerms->getTermsOfEntities(array, array, string)
#5 /srv/mediawiki/php-1.35.0-wmf.15/includes/api/ApiQuery.php(255): Wikibase\Client\Api\PageTerms->execute()
#6 /srv/mediawiki/php-1.35.0-wmf.15/includes/api/ApiMain.php(1603): ApiQuery->execute()
#7 /srv/mediawiki/php-1.35.0-wmf.15/includes/api/ApiMain.php(539): ApiMain->executeAction()
#8 /srv/mediawiki/php-1.35.0-wmf.15/includes/api/ApiMain.php(510): ApiMain->executeActionWithErrorHandling()
#9 /srv/mediawiki/php-1.35.0-wmf.15/api.php(78): ApiMain->execute()
#10 /srv/mediawiki/w/api.php(3): require(string)
#11 {main}
```
=== Impact ===
**Minimal.** Three occurrences in logstash over the last 30 days, one of them from me to test this. First seen 2020-01-16, not long after [all wikis to wmf.15](https://tools.wmflabs.org/sal/log/AW-uq0CafYQT6VcDocFF).
=== Notes ===
**Workaround** for API users: specify `wbptterms=label|description` (i. e. exclude aliases) or just `wbptterms=label` (as descriptions aren’t meaningful anyways, though reportedly [some do exist](https://twitter.com/Tpt93/status/1218256896102207488)).
Does not affect files without structured data ([example](https://commons.wikimedia.org/w/api.php?action=query&format=json&prop=pageterms&titles=File%3AWikidata-logo-en.svg) – [File:Wikidata-logo-en.svg](https://commons.wikimedia.org/wiki/File:Wikidata-logo-en.svg) has no structured data yet).