Talk pages of user accounts created between 21 March 2016 and 4 January 2017 give the following error: "Fatal exception of type MWContentSerializationException"
For example, see https://gom.wikipedia.org/wiki/वापरपी_चर्चा:STACEY_MESQUITA
I suspect that this is related to T154623 and the activity in T131957 around 4-6 January 2017.
---
```
Spotted in production:
#0 /srv/mediawiki/php-1.30.0-wmf.1/includes/Revision.php(1100): Flow\Content\BoardContentHandler->unserializeContent(string, string)
#1 /srv/mediawiki/php-1.30.0-wmf.1/includes/Revision.php(1063): Revision->getContentInternal()
#2 /srv/mediawiki/php-1.30.0-wmf.1/includes/page/WikiPage.php(666): Revision->getContent(integer, NULL)
#3 /srv/mediawiki/php-1.30.0-wmf.1/extensions/Flow/includes/WorkflowLoaderFactory.php(77): WikiPage->getContent()
#4 /srv/mediawiki/php-1.30.0-wmf.1/extensions/Flow/includes/Actions/Action.php(105): Flow\WorkflowLoaderFactory->createWorkflowLoader(Title)
#5 /srv/mediawiki/php-1.30.0-wmf.1/extensions/Flow/includes/Actions/ViewAction.php(20): Flow\Actions\FlowAction->showForAction(string, OutputPage)
#6 /srv/mediawiki/php-1.30.0-wmf.1/extensions/Flow/includes/Actions/Action.php(50): Flow\Actions\ViewAction->showForAction(string)
#7 /srv/mediawiki/php-1.30.0-wmf.1/includes/MediaWiki.php(499): Flow\Actions\FlowAction->show()
#8 /srv/mediawiki/php-1.30.0-wmf.1/includes/MediaWiki.php(293): MediaWiki->performAction(Article, Title)
#9 /srv/mediawiki/php-1.30.0-wmf.1/includes/MediaWiki.php(862): MediaWiki->performRequest()
#10 /srv/mediawiki/php-1.30.0-wmf.1/includes/MediaWiki.php(523): MediaWiki->main()
#11 /srv/mediawiki/php-1.30.0-wmf.1/index.php(43): MediaWiki->run()
#12 /srv/mediawiki/w/index.php(3): include(string)
#13 {main}
```