I saw this in the logs today
2015-04-12 08:00:15 translatewiki.net translatewiki_net-bw_: [ac0f8a96] /w/i.php?title=Special:Translate&group=ext-0-all&language=de&tux=0&limit=1000 MWException from line 3633 of /srv/mediawiki/tags/2015-04-10_10:04:17/includes/User.php: CAS update failed on user_touched for user ID '1509'.
#0 /srv/mediawiki/tags/2015-04-10_10:04:17/extensions/Translate/api/ApiTranslateUser.php(82): User->saveSettings()
#1 /srv/mediawiki/tags/2015-04-10_10:04:17/extensions/Translate/specials/SpecialTranslate.php(214): ApiTranslateUser::trackGroup(Object(AggregateMessageGroup), Object(User))
#2 /srv/mediawiki/tags/2015-04-10_10:04:17/includes/specialpage/SpecialPage.php(384): SpecialTranslate->execute(NULL)
#3 /srv/mediawiki/tags/2015-04-10_10:04:17/includes/specialpage/SpecialPageFactory.php(581): SpecialPage->run(NULL)
#4 /srv/mediawiki/tags/2015-04-10_10:04:17/includes/MediaWiki.php(267): SpecialPageFactory::executePath(Object(Title), Object(RequestContext))
#5 /srv/mediawiki/tags/2015-04-10_10:04:17/includes/MediaWiki.php(566): MediaWiki->performRequest()
#6 /srv/mediawiki/tags/2015-04-10_10:04:17/includes/MediaWiki.php(414): MediaWiki->main()
#7 /srv/mediawiki/tags/2015-04-10_10:04:17/index.php(46): MediaWiki->run()
# What does it mean? Preference was not updated?
# Is there a bug in my code?
# Is there a bug somewhere else?