Train presync currently fails consistently with:
13:43:57 Checking for new runtime errors locally
'mwscript eval.php --wiki testcommonswiki' generated unexpected output: [09ce253dddc525fa8d86a8b6] [no req] UnexpectedValueException: Section 's4' has no hosts defined.
Backtrace:
from /srv/mediawiki-staging/php-1.44.0-wmf.3/includes/libs/rdbms/lbfactory/LBFactoryMulti.php(177)
#0 /srv/mediawiki-staging/php-1.44.0-wmf.3/includes/libs/rdbms/lbfactory/LBFactoryMulti.php(226): Wikimedia\Rdbms\LBFactoryMulti->newMainLB(bool)
#1 /srv/mediawiki-staging/php-1.44.0-wmf.3/includes/db/MWLBFactory.php(420): Wikimedia\Rdbms\LBFactoryMulti->getMainLB()
#2 /srv/mediawiki-staging/php-1.44.0-wmf.3/includes/ServiceWiring.php(731): MWLBFactory->applyGlobalState(Wikimedia\Rdbms\LBFactoryMulti, MediaWiki\Config\GlobalVarConfig, Wikimedia\Stats\BufferingStatsdDataFactory)
#3 /srv/mediawiki-staging/php-1.44.0-wmf.3/vendor/wikimedia/services/src/ServiceContainer.php(442): Wikimedia\Services\ServiceContainer::{closure}(MediaWiki\MediaWikiServices)
#4 /srv/mediawiki-staging/php-1.44.0-wmf.3/vendor/wikimedia/services/src/ServiceContainer.php(406): Wikimedia\Services\ServiceContainer->createService(string)
#5 /srv/mediawiki-staging/php-1.44.0-wmf.3/includes/MediaWikiServices.php(357): Wikimedia\Services\ServiceContainer->getService(string)
#6 /srv/mediawiki-staging/php-1.44.0-wmf.3/includes/MediaWikiServices.php(1064): MediaWiki\MediaWikiServices->getService(string)
#7 /srv/mediawiki-staging/php-1.44.0-wmf.3/includes/ServiceWiring.php(1407): MediaWiki\MediaWikiServices->getDBLoadBalancerFactory()
#8 /srv/mediawiki-staging/php-1.44.0-wmf.3/vendor/wikimedia/services/src/ServiceContainer.php(442): Wikimedia\Services\ServiceContainer::{closure}(MediaWiki\MediaWikiServices)
#9 /srv/mediawiki-staging/php-1.44.0-wmf.3/vendor/wikimedia/services/src/ServiceContainer.php(406): Wikimedia\Services\ServiceContainer->createService(string)
#10 /srv/mediawiki-staging/php-1.44.0-wmf.3/includes/MediaWikiServices.php(357): Wikimedia\Services\ServiceContainer->getService(string)
#11 /srv/mediawiki-staging/php-1.44.0-wmf.3/includes/MediaWikiServices.php(1495): MediaWiki\MediaWikiServices->getService(string)
#12 /srv/mediawiki-staging/php-1.44.0-wmf.3/includes/ServiceWiring.php(501): MediaWiki\MediaWikiServices->getNameTableStoreFactory()
#13 /srv/mediawiki-staging/php-1.44.0-wmf.3/vendor/wikimedia/services/src/ServiceContainer.php(442): Wikimedia\Services\ServiceContainer::{closure}(MediaWiki\MediaWikiServices)
#14 /srv/mediawiki-staging/php-1.44.0-wmf.3/vendor/wikimedia/services/src/ServiceContainer.php(406): Wikimedia\Services\ServiceContainer->createService(string)
#15 /srv/mediawiki-staging/php-1.44.0-wmf.3/includes/MediaWikiServices.php(357): Wikimedia\Services\ServiceContainer->getService(string)
#16 /srv/mediawiki-staging/php-1.44.0-wmf.3/vendor/wikimedia/services/src/ServiceContainer.php(414): MediaWiki\MediaWikiServices->getService(string)
#17 /srv/mediawiki-staging/php-1.44.0-wmf.3/vendor/wikimedia/object-factory/src/ObjectFactory.php(204): Wikimedia\Services\ServiceContainer->get(string)
#18 /srv/mediawiki-staging/php-1.44.0-wmf.3/vendor/wikimedia/object-factory/src/ObjectFactory.php(149): Wikimedia\ObjectFactory\ObjectFactory::getObjectFromSpec(array, array)
#19 /srv/mediawiki-staging/php-1.44.0-wmf.3/includes/HookContainer/HookContainer.php(256): Wikimedia\ObjectFactory\ObjectFactory->createObject(array)
#20 /srv/mediawiki-staging/php-1.44.0-wmf.3/includes/HookContainer/HookContainer.php(351): MediaWiki\HookContainer\HookContainer->makeExtensionHandlerCallback(string, array, array)
#21 /srv/mediawiki-staging/php-1.44.0-wmf.3/includes/HookContainer/HookContainer.php(527): MediaWiki\HookContainer\HookContainer->normalizeHandler(string, array, array)
#22 /srv/mediawiki-staging/php-1.44.0-wmf.3/includes/HookContainer/HookContainer.php(146): MediaWiki\HookContainer\HookContainer->getHandlers(string, array)
#23 /srv/mediawiki-staging/php-1.44.0-wmf.3/includes/HookContainer/HookRunner.php(3496): MediaWiki\HookContainer\HookContainer->run(string, array)
#24 /srv/mediawiki-staging/php-1.44.0-wmf.3/includes/Setup.php(454): MediaWiki\HookContainer\HookRunner->onSetupAfterCache()
#25 /srv/mediawiki-staging/php-1.44.0-wmf.3/maintenance/run.php(49): require_once(string)
#26 /srv/mediawiki-staging/multiversion/MWScript.php(158): require_once(string)
#27 {main}This is the same deployment stage where error T379044 was happening last week for "testwiki". It seems there is no connection and it's most likely just a coincidence. Do note however the MW script mentioned above is running inside a Docker container.
Interestingly enough, there were a couple of backports this morning and they were not affected by this.