Hi, im seeing this in the logs for mw 1.31 running php 7.2, we use CentralAuth.
InvalidArgumentException from line 1512 of /srv/mediawiki/w/includes/Block.php: Blocker must be a local user or a name that cannot be a local user #0 /srv/mediawiki/w/includes/Block.php(461): Block->setBlocker(User) #1 /srv/mediawiki/w/includes/Block.php(492): Block->initFromRow(stdClass) #2 /srv/mediawiki/w/includes/Block.php(362): Block::newFromRow(stdClass) #3 /srv/mediawiki/w/includes/Block.php(1195): Block->newLoad(NULL) #4 /srv/mediawiki/w/includes/page/Article.php(768): Block::newFromTarget(string, NULL) #5 /srv/mediawiki/w/includes/page/Article.php(667): Article->getRobotPolicy(string, ParserOutput) #6 /srv/mediawiki/w/includes/actions/ViewAction.php(68): Article->view() #7 /srv/mediawiki/w/includes/MediaWiki.php(500): ViewAction->show() #8 /srv/mediawiki/w/includes/MediaWiki.php(294): MediaWiki->performAction(Article, Title) #9 /srv/mediawiki/w/includes/MediaWiki.php(861): MediaWiki->performRequest() #10 /srv/mediawiki/w/includes/MediaWiki.php(524): MediaWiki->main() #11 /srv/mediawiki/w/index.php(42): MediaWiki->run() #12 {main}