Reported by @Etonkovidova at https://phabricator.wikimedia.org/T110358#1576773:
"
In betalabs it happens only when a board description has a template(any template) and that template was deleted and 'Save changes' was clicked:
Delete a content from a board descirption. In wikitext code - add [[Category:Flow|*]] - click on 'Save description'
"
(Adding the category is not needed to reproduce).
The following error is displayed:
[32ec9d4d] Exception Caught: Row has null primary key:
2015-08-26 19:42:35 deployment-mediawiki02 enwiki exception ERROR: [32ec9d4d] /w/api.php Flow\Exception\DataPersistenceException from line 117 of /srv/mediawiki/php-master/extensions/Flow/includes/Data/Storage/BasicDbStorage.php: Row has null primary key: {"exception":"[Exception Flow\\Exception\\DataPersistenceException] (/srv/mediawiki/php-master/extensions/Flow/includes/Data/Storage/BasicDbStorage.php:117) Row has null primary key: [stacktrace] #0 /srv/mediawiki/php-master/extensions/Flow/includes/Data/ObjectManager.php(187): Flow\\Data\\Storage\\BasicDbStorage->remove(array) #1 /srv/mediawiki/php-master/extensions/Flow/includes/Data/ObjectManager.php(202): Flow\\Data\\ObjectManager->remove(Flow\\Model\\WikiReference, array) #2 /srv/mediawiki/php-master/extensions/Flow/includes/Data/ManagerGroup.php(97): Flow\\Data\\ObjectManager->multiRemove(array, array) #3 /srv/mediawiki/php-master/extensions/Flow/includes/Data/ManagerGroup.php(114): Flow\\Data\\ManagerGroup->multiMethod(string, array, array) #4 /srv/mediawiki/php-master/extensions/Flow/includes/Data/Listener/ReferenceRecorder.php(77): Flow\\Data\\ManagerGroup->multiRemove(array) #5 /srv/mediawiki/php-master/extensions/Flow/includes/Data/ObjectManager.php(261): Flow\\Data\\Listener\\ReferenceRecorder->onAfterInsert(Flow\\Model\\Header, array, array) #6 /srv/mediawiki/php-master/extensions/Flow/includes/Data/ObjectManager.php(170): Flow\\Data\\ObjectManager->insert(array, array) #7 /srv/mediawiki/php-master/extensions/Flow/includes/Data/ObjectManager.php(143): Flow\\Data\\ObjectManager->multiPut(array, array) #8 /srv/mediawiki/php-master/extensions/Flow/includes/Data/ManagerGroup.php(80): Flow\\Data\\ObjectManager->put(Flow\\Model\\Header, array) #9 /srv/mediawiki/php-master/extensions/Flow/includes/Block/Header.php(175): Flow\\Data\\ManagerGroup->put(Flow\\Model\\Header, array) #10 /srv/mediawiki/php-master/extensions/Flow/includes/SubmissionHandler.php(141): Flow\\Block\\HeaderBlock->commit() #11 /srv/mediawiki/php-master/extensions/Flow/includes/WorkflowLoader.php(66): Flow\\SubmissionHandler->commit(Flow\\Model\\Workflow, array) #12 /srv/mediawiki/php-master/extensions/Flow/includes/Api/ApiFlowBasePost.php(41): Flow\\WorkflowLoader->commit(array) #13 /srv/mediawiki/php-master/extensions/Flow/includes/Api/ApiFlow.php(106): Flow\\Api\\ApiFlowBasePost->execute() #14 /srv/mediawiki/php-master/includes/api/ApiMain.php(1093): Flow\\Api\\ApiFlow->execute() #15 /srv/mediawiki/php-master/includes/api/ApiMain.php(432): ApiMain->executeAction() #16 /srv/mediawiki/php-master/includes/api/ApiMain.php(405): ApiMain->executeActionWithErrorHandling() #17 /srv/mediawiki/php-master/api.php(88): ApiMain->execute() #18 /srv/mediawiki/w/api.php(3): include(string) #19 {main} "}
This is probably somehow related to T107204: Separate reference tables by wiki