About 35 events a day are being lost due to this error appearing in logstash meaning we are likely dropping 35 events a day in our schema. Probably not a big deal but would be interesting to understand the cause of this bug to inform future developments.
Sam has suggested we move away from using the class on the body tag in our instrumentation and use mw.config directly.
at logEvent URL1:95:542 at URL1:96:12 URL1: https://fr.wikipedia.org/w/load.php?lang=fr&modules=ext.centralNotice.choiceData%2Cdisplay%2CgeoIP%2CkvStore%2CstartUp%7Cext.centralauth.centralautologin%7Cext.cite.ux-enhancements%7Cext.cx.eventlogging.campaigns%7Cext.eventLogging%2CnavigationTiming%2Cpopups%2CwikimediaEvents%7Cext.growthExperiments.SuggestedEditSession%7Cext.quicksurveys.init%2Clib%7Cext.uls.common%2Ccompactlinks%2Cinit%2Cinterface%2Cpreferences%2Cwebfonts%7Cjquery%2Coojs%2Coojs-router%2Coojs-ui-core%2Coojs-ui-widgets%2Csite%7Cjquery.client%2Ccookie%2CtextSelection%7Cjquery.uls.data%7Cmediawiki.String%2CTitle%2CUri%2Capi%2Cbase%2Ccldr%2Ccookie%2Cexperiments%2CjqueryMsg%2Clanguage%2Cstorage%2Cuser%2Cutil%2Cviewport%7Cmediawiki.editfont.styles%7Cmediawiki.libs.pluralruleparser%7Cmediawiki.page.ready%7Cmediawiki.ui.button%7Cmmv.bootstrap%2Chead%7Cmmv.bootstrap.autostart%7Coojs-ui-core.icons%2Cstyles%7Coojs-ui-widgets.icons%7Coojs-ui.styles.indicators%7Cskins.vector.js%7Cuser.defaults&skin=vector&version=1l4fr