=== Error ===
Request URL: https://mh.wiktionary.org/w/index.php?title=Main_Page&action=info
Request ID: `XOO8XgpAIC4AALtisD0AAACH`
```name=message
PHP Warning: Linker::userLink received an empty username. Are there database errors that need to be fixed? [Called from Linker::userLink in /srv/mediawiki/php-1.34.0-wmf.5/includes/Linker.php at line 899]
```
```name=trace,lines=10
#0 /srv/mediawiki/php-1.34.0-wmf.5/includes/debug/MWDebug.php(309): MWExceptionHandler::handleError(integer, string, string, integer, array, array)
#1 /srv/mediawiki/php-1.34.0-wmf.5/includes/debug/MWDebug.php(164): MWDebug::sendMessage(string, array, string, integer)
#2 /srv/mediawiki/php-1.34.0-wmf.5/includes/GlobalFunctions.php(1069): MWDebug::warning(string, integer, integer, string)
#3 /srv/mediawiki/php-1.34.0-wmf.5/includes/Linker.php(899): wfLogWarning(string)
#4 /srv/mediawiki/php-1.34.0-wmf.5/includes/Linker.php(1126): Linker::userLink(integer, string)
#5 /srv/mediawiki/php-1.34.0-wmf.5/includes/actions/InfoAction.php(564): Linker::revUserTools(Revision)
#6 /srv/mediawiki/php-1.34.0-wmf.5/includes/actions/InfoAction.php(120): InfoAction->pageInfo()
#7 /srv/mediawiki/php-1.34.0-wmf.5/includes/actions/FormlessAction.php(43): InfoAction->onView()
#8 /srv/mediawiki/php-1.34.0-wmf.5/includes/MediaWiki.php(499): FormlessAction->show()
#9 /srv/mediawiki/php-1.34.0-wmf.5/includes/MediaWiki.php(294): MediaWiki->performAction(Article, Title)
#10 /srv/mediawiki/php-1.34.0-wmf.5/includes/MediaWiki.php(865): MediaWiki->performRequest()
#11 /srv/mediawiki/php-1.34.0-wmf.5/includes/MediaWiki.php(515): MediaWiki->main()
#12 /srv/mediawiki/php-1.34.0-wmf.5/index.php(42): MediaWiki->run()
#13 /srv/mediawiki/w/index.php(3): include(string)
#14 {main}
```
=== Impact ===
This error indicates MediaWiki is unable to render a link to a username despite the code expecting to be able to do so.
This happens on the "Page information" action, for the "Page creator" field. The impact is that for a number of pages this now says: "(no username available)"
Example: https://wikitech.wikimedia.org/w/index.php?title=Main_Page&action=info
| Page creator |** (no username available) (no username available)**
|--
| Date of page creation | 23:18, 10 June 2004 ( https://wikitech.wikimedia.org/w/index.php?title=Main_Page&oldid=12270 )
|--
Apparently when trying to retrieve the username for the first page creation (based on pageinfo-firstuser). Which is a revision by the MediaWiki installer / addWiki:
https://wikitech.wikimedia.org/w/index.php?title=Main_Page&dir=prev&limit=1&action=history
So that is most probably a very old bug from `includes/actions/InfoAction.php`
=== Notes ===
Started with 1.34-wmf.4, triggered about 5,000 times per week.
{F29234050}