While trying to test T238043 with a script, I end up with this:
... 14200 (11.52 pages/sec 11.52 revs/sec)> ] 22% ETA 1:12:18 14300 (11.52 pages/sec 11.52 revs/sec)> ] 22% ETA 1:12:11 14400 (11.52 pages/sec 11.52 revs/sec)> ] 22% ETA 1:11:58 CannotCreateActorException from line 2282 of /opt/htdocs/mediawiki/includes/user/User.php: Cannot create an actor for a usable name that is not an existing user #0 /opt/htdocs/mediawiki/includes/ActorMigration.php(303): User->getActorId(Object(Wikimedia\Rdbms\DatabaseMysqli)) #1 /opt/htdocs/mediawiki/includes/Revision/RevisionStore.php(753): ActorMigration->getInsertValuesWithTempTable(Object(Wikimedia\Rdbms\DatabaseMysqli), 'rev_user', Object(User)) #2 /opt/htdocs/mediawiki/includes/Revision/RevisionStore.php(552): MediaWiki\Revision\RevisionStore->insertRevisionRowOn(Object(Wikimedia\Rdbms\DatabaseMysqli), Object(MediaWiki\Revision\MutableRevisionRecord), Object(Title), 0) #3 /opt/htdocs/mediawiki/includes/Revision/RevisionStore.php(490): MediaWiki\Revision\RevisionStore->insertRevisionInternal(Object(MediaWiki\Revision\MutableRevisionRecord), Object(Wikimedia\Rdbms\DatabaseMysqli), Object(User), Object(CommentStoreComment), Object(Title), 14467, 0) #4 /opt/htdocs/mediawiki/includes/libs/rdbms/database/Database.php(3966): MediaWiki\Revision\RevisionStore->MediaWiki\Revision\{closure}(Object(Wikimedia\Rdbms\DatabaseMysqli), 'MediaWiki\\Revis...') #5 /opt/htdocs/mediawiki/includes/libs/rdbms/database/DBConnRef.php(68): Wikimedia\Rdbms\Database->doAtomicSection('MediaWiki\\Revis...', Object(Closure)) #6 /opt/htdocs/mediawiki/includes/libs/rdbms/database/DBConnRef.php(635): Wikimedia\Rdbms\DBConnRef->__call('doAtomicSection', Array) #7 /opt/htdocs/mediawiki/includes/Revision/RevisionStore.php(498): Wikimedia\Rdbms\DBConnRef->doAtomicSection('MediaWiki\\Revis...', Object(Closure)) #8 /opt/htdocs/mediawiki/includes/Revision.php(968): MediaWiki\Revision\RevisionStore->insertRevisionOn(Object(MediaWiki\Revision\MutableRevisionRecord), Object(Wikimedia\Rdbms\DBConnRef)) #9 /opt/htdocs/mediawiki/includes/import/ImportableOldRevisionImporter.php(129): Revision->insertOn(Object(Wikimedia\Rdbms\DBConnRef)) #10 /opt/htdocs/mediawiki/includes/import/WikiRevision.php(616): ImportableOldRevisionImporter->import(Object(WikiRevision)) #11 /opt/htdocs/mediawiki/includes/import/WikiImporter.php(366): WikiRevision->importOldRevision() #12 /opt/htdocs/mediawiki/maintenance/importDump.php(209): WikiImporter->importRevision(Object(WikiRevision)) #13 /opt/htdocs/mediawiki/includes/import/WikiImporter.php(501): BackupReader->handleRevision(Object(WikiRevision), Object(WikiImporter)) #14 /opt/htdocs/mediawiki/includes/import/WikiImporter.php(941): WikiImporter->revisionCallback(Object(WikiRevision)) #15 /opt/htdocs/mediawiki/includes/import/WikiImporter.php(860): WikiImporter->processRevision(Array, Array) #16 /opt/htdocs/mediawiki/includes/import/WikiImporter.php(802): WikiImporter->handleRevision(Array) #17 /opt/htdocs/mediawiki/includes/import/WikiImporter.php(606): WikiImporter->handlePage() #18 /opt/htdocs/mediawiki/maintenance/importDump.php(359): WikiImporter->doImport() #19 /opt/htdocs/mediawiki/maintenance/importDump.php(301): BackupReader->importFromHandle(Resource id #252) #20 /opt/htdocs/mediawiki/maintenance/importDump.php(129): BackupReader->importFromStdin() #21 /opt/htdocs/mediawiki/maintenance/doMaintenance.php(99): BackupReader->execute() #22 /opt/htdocs/mediawiki/maintenance/importDump.php(364): require_once('/opt/htdocs/med...') #23 {main} [f2e33a53a89f4bbd09627f75] [no req] Wikimedia\Rdbms\DBTransactionError from line 1680 of /opt/htdocs/mediawiki/includes/libs/rdbms/loadbalancer/LoadBalancer.php: BackupReader: Commit failed on server(s) localhost: Cannot execute query from BackupReader while transaction status is ERROR Backtrace: #0 /opt/htdocs/mediawiki/includes/libs/rdbms/lbfactory/LBFactory.php(208): Wikimedia\Rdbms\LoadBalancer->commitMasterChanges(string, integer) #1 /opt/htdocs/mediawiki/includes/libs/rdbms/lbfactory/LBFactorySimple.php(134): Wikimedia\Rdbms\LBFactory->Wikimedia\Rdbms\{closure}(Wikimedia\Rdbms\LoadBalancer, string, array) #2 /opt/htdocs/mediawiki/includes/libs/rdbms/lbfactory/LBFactory.php(210): Wikimedia\Rdbms\LBFactorySimple->forEachLB(Closure, array) #3 /opt/htdocs/mediawiki/includes/libs/rdbms/lbfactory/LBFactory.php(273): Wikimedia\Rdbms\LBFactory->forEachLBCallMethod(string, array) #4 /opt/htdocs/mediawiki/maintenance/doMaintenance.php(124): Wikimedia\Rdbms\LBFactory->commitMasterChanges(string) #5 /opt/htdocs/mediawiki/maintenance/importDump.php(364): require_once(string) #6 {main}