In T308074#8089506, @colewhite wrote:

Seeing an increased rate of warnings on the "session" channel since deployment:

Metadata merge failed: MediaWiki\\Session\\MetadataMergeException: Key \"rights\" changed in /srv/mediawiki/php-1.39.0-wmf.21/includes/session/SessionProvider.php:331
Stack trace:
#0 /srv/mediawiki/php-1.39.0-wmf.21/includes/session/SessionManager.php(678): MediaWiki\\Session\\SessionProvider->mergeMetadata(Array, Array)
#1 /srv/mediawiki/php-1.39.0-wmf.21/includes/session/SessionManager.php(546): MediaWiki\\Session\\SessionManager->loadSessionInfoFromStore(Object(MediaWiki\\Session\\SessionInfo), Object(WebRequest))
#2 /srv/mediawiki/php-1.39.0-wmf.21/includes/session/SessionManager.php(248): MediaWiki\\Session\\SessionManager->getSessionInfoForRequest(Object(WebRequest))
#3 /srv/mediawiki/php-1.39.0-wmf.21/includes/WebRequest.php(842): MediaWiki\\Session\\SessionManager->getSessionForRequest(Object(WebRequest))
#4 /srv/mediawiki/php-1.39.0-wmf.21/includes/session/SessionManager.php(169): WebRequest->getSession()
#5 /srv/mediawiki/php-1.39.0-wmf.21/includes/Setup.php(448): MediaWiki\\Session\\SessionManager::getGlobalSession()
#6 /srv/mediawiki/php-1.39.0-wmf.21/includes/WebStart.php(86): require_once('/srv/mediawiki/...')
#7 /srv/mediawiki/php-1.39.0-wmf.21/api.php(43): require('/srv/mediawiki/...')
#8 /srv/mediawiki/w/api.php(3): require('/srv/mediawiki/...')
#9 {main}

Note: these warnings are in the dlq-* indexes will not show up in the default logstash-* indexes. There is a type conflict with CentralAuth over the new_value key.

This began after deployment of 1.39.0-wmf.21