I used `action=flow&submodule=new-topic` on an empty page on testwiki where I have the flow-bot right and thanks to T76793 that created a Flow board! \o/ (It's https://test.wikipedia.org/wiki/User_Talk%253SPage_%28WMF%29/NewTopic because I goofed on escaping the colon in my cURL request ).
However, when I try to edit the header of this Flow board as a regular user, the API request fails. The API response to view-header (if you click the pencil icon) or edit-header (if you open the pencil icon link in a new page) is a 503 Wikimedia Error HTML page, and the user sees a pink
> An error occurred while contacting the server.
hhvm.log contains
Dec 29 20:50:30 mw1017: #012Notice: Undefined index: flowdb:flow_workflow:title:v2::0:User_Talk%253SPage_(WMF)/NewTopic:discussion:testwiki:4.5 in /srv/mediawiki/php-1.25wmf13/extensions/Flow/includes/Data/Compactor/FeatureCompactor.php on line 69
Dec 29 20:50:30 mw1017: #012Warning: Invalid argument supplied for foreach() in /srv/mediawiki/php-1.25wmf13/extensions/Flow/includes/Data/Compactor/FeatureCompactor.php on line 74
Dec 29 20:50:30 mw1017: #012Fatal error: Invalid operand type was used: cannot perform this operation with arrays in /srv/mediawiki/php-1.25wmf13/extensions/Flow/includes/Data/Compactor/FeatureCompactor.php on line 81
Dec 29 20:50:30 mw1017: #012Notice: Undefined index: flowdb:flow_workflow:title:v2::0:User_Talk%253SPage_(WMF)/NewTopic:discussion:testwiki:4.5 in /srv/mediawiki/php-1.25wmf13/extensions/Flow/includes/Data/Compactor/FeatureCompactor.php on line 69
Dec 29 20:50:30 mw1017: #012Warning: Invalid argument supplied for foreach() in /srv/mediawiki/php-1.25wmf13/extensions/Flow/includes/Data/Compactor/FeatureCompactor.php on line 74
Dec 29 20:50:30 mw1017: #012Fatal error: Invalid operand type was used: cannot perform this operation with arrays in /srv/mediawiki/php-1.25wmf13/extensions/Flow/includes/Data/Compactor/FeatureCompactor.php on line 81
Editing the header of a board for the first time often regresses. It could be a cache issue (that index looks like a cache key), or the garbled page title, or...