I can't reproduce it manually but when I run opt_in.feature:39 it fails to restore my old Flow board and I get those errors in mediawiki-exception.log
2015-11-02 15:56:36 mediawiki-vagrant wiki: [fa9e1f22] /wiki/Special:Preferences DBQueryError from line 1090 of /vagrant/mediawiki/includes/db/Database.php: A database error has occurred. Did you forget to run maintenance/update.php after upgrading? See: https://www.mediawiki.org/wiki/Manual:Upgrading#Run_the_update_script Query: UPDATE `page` SET page_namespace = '3',page_title = 'New_user_41489056023297023477480316229385360764' WHERE page_id = '7433' Function: MovePage::moveToInternal Error: 1062 Duplicate entry '3-New_user_41489056023297023477480316229385360764' for key 'name_title' (127.0.0.1) #0 /vagrant/mediawiki/includes/db/Database.php(1047): DatabaseBase->reportQueryError(string, integer, string, string, boolean) #1 /vagrant/mediawiki/includes/db/Database.php(2001): DatabaseBase->query(string, string) #2 /vagrant/mediawiki/includes/MovePage.php(488): DatabaseBase->update(string, array, array, string) #3 /vagrant/mediawiki/includes/MovePage.php(255): MovePage->moveToInternal(User, Title, string, boolean) #4 /vagrant/mediawiki/extensions/Flow/includes/Import/OptInController.php(143): MovePage->move(User, string, boolean) #5 /vagrant/mediawiki/extensions/Flow/includes/Import/OptInController.php(344): Flow\Import\OptInController->movePage(Title, Title, string) #6 /vagrant/mediawiki/extensions/Flow/includes/Import/OptInController.php(90): Flow\Import\OptInController->restoreExistingFlowBoard(Title, Title, NULL) #7 /vagrant/mediawiki/extensions/Flow/includes/Import/OptInUpdate.php(48): Flow\Import\OptInController->enable(Title, User) #8 /vagrant/mediawiki/includes/deferred/DeferredUpdates.php(129): Flow\Import\OptInUpdate->doUpdate() #9 /vagrant/mediawiki/includes/MediaWiki.php(693): DeferredUpdates::doUpdates(string) #10 /vagrant/mediawiki/includes/MediaWiki.php(540): MediaWiki->restInPeace(string) #11 [internal function]: Closure$MediaWiki::doPostOutputShutdown() #12 {main} 2015-11-02 15:56:36 mediawiki-vagrant wiki: [b0587686] /wiki/Special:Preferences DBUnexpectedError from line 3528 of /vagrant/mediawiki/includes/db/Database.php: Got COMMIT while atomic sections MovePage::move are still open #0 /vagrant/mediawiki/includes/db/loadbalancer/LoadBalancer.php(1039): DatabaseBase->commit(string, string) #1 /vagrant/mediawiki/includes/db/loadbalancer/LBFactory.php(186): LoadBalancer->commitMasterChanges() #2 /vagrant/mediawiki/includes/db/loadbalancer/LBFactorySimple.php(155): Closure$LBFactory::forEachLBCallMethod(LoadBalancer, string, array) #3 /vagrant/mediawiki/includes/db/loadbalancer/LBFactory.php(187): LBFactorySimple->forEachLB(Closure$LBFactory::forEachLBCallMethod;474060173, array) #4 /vagrant/mediawiki/includes/db/loadbalancer/LBFactory.php(204): LBFactory->forEachLBCallMethod(string) #5 /vagrant/mediawiki/includes/deferred/DeferredUpdates.php(130): LBFactory->commitMasterChanges() #6 /vagrant/mediawiki/includes/MediaWiki.php(693): DeferredUpdates::doUpdates(string) #7 /vagrant/mediawiki/includes/MediaWiki.php(540): MediaWiki->restInPeace(string) #8 [internal function]: Closure$MediaWiki::doPostOutputShutdown() #9 {main} 2015-11-02 15:56:36 mediawiki-vagrant wiki: [c93a0e72] /wiki/Special:Preferences DBUnexpectedError from line 3528 of /vagrant/mediawiki/includes/db/Database.php: Got COMMIT while atomic sections MovePage::move are still open #0 /vagrant/mediawiki/includes/db/loadbalancer/LoadBalancer.php(1039): DatabaseBase->commit(string, string) #1 /vagrant/mediawiki/includes/db/loadbalancer/LBFactory.php(186): LoadBalancer->commitMasterChanges() #2 /vagrant/mediawiki/includes/db/loadbalancer/LBFactorySimple.php(155): Closure$LBFactory::forEachLBCallMethod(LoadBalancer, string, array) #3 /vagrant/mediawiki/includes/db/loadbalancer/LBFactory.php(187): LBFactorySimple->forEachLB(Closure$LBFactory::forEachLBCallMethod;474060173, array) #4 /vagrant/mediawiki/includes/db/loadbalancer/LBFactory.php(204): LBFactory->forEachLBCallMethod(string) #5 /vagrant/mediawiki/includes/deferred/DeferredUpdates.php(130): LBFactory->commitMasterChanges() #6 /vagrant/mediawiki/includes/MediaWiki.php(693): DeferredUpdates::doUpdates(string) #7 /vagrant/mediawiki/includes/MediaWiki.php(540): MediaWiki->restInPeace(string) #8 [internal function]: Closure$MediaWiki::doPostOutputShutdown() #9 {main} 2015-11-02 15:56:36 mediawiki-vagrant wiki: [4a9ef772] /wiki/Special:Preferences DBUnexpectedError from line 3528 of /vagrant/mediawiki/includes/db/Database.php: Got COMMIT while atomic sections MovePage::move are still open #0 /vagrant/mediawiki/includes/db/loadbalancer/LoadBalancer.php(1039): DatabaseBase->commit(string, string) #1 /vagrant/mediawiki/includes/db/loadbalancer/LBFactory.php(186): LoadBalancer->commitMasterChanges() #2 /vagrant/mediawiki/includes/db/loadbalancer/LBFactorySimple.php(155): Closure$LBFactory::forEachLBCallMethod(LoadBalancer, string, array) #3 /vagrant/mediawiki/includes/db/loadbalancer/LBFactory.php(187): LBFactorySimple->forEachLB(Closure$LBFactory::forEachLBCallMethod;474060173, array) #4 /vagrant/mediawiki/includes/db/loadbalancer/LBFactory.php(204): LBFactory->forEachLBCallMethod(string) #5 /vagrant/mediawiki/includes/deferred/DeferredUpdates.php(130): LBFactory->commitMasterChanges() #6 /vagrant/mediawiki/includes/MediaWiki.php(693): DeferredUpdates::doUpdates(string) #7 /vagrant/mediawiki/includes/MediaWiki.php(540): MediaWiki->restInPeace(string) #8 [internal function]: Closure$MediaWiki::doPostOutputShutdown() #9 {main} 2015-11-02 15:56:36 mediawiki-vagrant wiki: [4b3dca5f] /wiki/Special:Preferences DBUnexpectedError from line 3528 of /vagrant/mediawiki/includes/db/Database.php: Got COMMIT while atomic sections MovePage::move are still open #0 /vagrant/mediawiki/includes/db/loadbalancer/LoadBalancer.php(1039): DatabaseBase->commit(string, string) #1 /vagrant/mediawiki/includes/db/loadbalancer/LBFactory.php(186): LoadBalancer->commitMasterChanges() #2 /vagrant/mediawiki/includes/db/loadbalancer/LBFactorySimple.php(155): Closure$LBFactory::forEachLBCallMethod(LoadBalancer, string, array) #3 /vagrant/mediawiki/includes/db/loadbalancer/LBFactory.php(187): LBFactorySimple->forEachLB(Closure$LBFactory::forEachLBCallMethod;474060173, array) #4 /vagrant/mediawiki/includes/db/loadbalancer/LBFactory.php(204): LBFactory->forEachLBCallMethod(string) #5 /vagrant/mediawiki/includes/MediaWiki.php(709): LBFactory->commitMasterChanges() #6 /vagrant/mediawiki/includes/MediaWiki.php(540): MediaWiki->restInPeace(string) #7 [internal function]: Closure$MediaWiki::doPostOutputShutdown() #8 {main}