About 200/minute, for 10 minutes, around 2019-05-28 14:00 UTC (dashboard).
PHP Fatal Error: Uncaught Error: Call to undefined method CommentStore::getCommentInternal() in /srv/mediawiki/php-1.34.0-wmf.6/includes/CommentStore.php:448
Stack trace:
#0 /srv/mediawiki/php-1.34.0-wmf.6/includes/Revision/RevisionStore.php(1808): CommentStore->getCommentLegacy(Wikimedia\Rdbms\DBConnRef, string, stdClass, boolean)
#1 /srv/mediawiki/php-1.34.0-wmf.6/includes/Revision/RevisionStore.php(2167): MediaWiki\Revision\RevisionStore->newRevisionFromRow(stdClass, integer, Title)
#2 /srv/mediawiki/php-1.34.0-wmf.6/includes/Revision/RevisionStore.php(1535): MediaWiki\Revision\RevisionStore->loadRevisionFromConds(Wikimedia\Rdbms\DBConnRef, array, integer, Title)
#3 /srv/mediawiki/php-1.34.0-wmf.6/includes/Revision.php(138): MediaWiki\Revision\RevisionStore->getRevisionByTitle(Title, integer, integer)
#4 /srv/mediawiki/php-1.34.0-wmf.6/includes/actions/RawAction.php(190): Revision::newFromTitle(Title, integer)
#5 /srv/mediawiki/php-1.34.0-wmf.6/includes/actions/RawAction.php(159): RawAction->getRawText()
#6 /srv/mediawiki/php-1.34.0-wmf.6/includes/actions/FormlessAction.php(43): RawAction->onView()
#7 /srv/mediawiki/php-1.34.0-wmf.6/includes/MediaWiki.php(499): FormlessAction->show()
#8 /srv/mediawiki/php-1.34.0-wmf.6/includes/MediaWiki.php(294): MediaWiki->performAction(Article, Title)
#9 /srv/mediawiki/php-1.34.0-wmf.6/includes/MediaWiki.php(865): MediaWiki->performRequest()
#10 /srv/mediawiki/php-1.34.0-wmf.6/includes/MediaWiki.php(515): MediaWiki->main()
#11 /srv/mediawiki/php-1.34.0-wmf.6/index.php(42): MediaWiki->run()
#12 /srv/mediawiki/w/index.php(3): require(string)
#13 {main}From the timing it seems like a train deploy byproduct, but went on pretty long for that, and affected group2 wikis.
(Also, the stack trace is cut off in PHP 7.2. Is that a known issue?)