I'm trying to upgrade a mediawiki installation to 1.26 and it seems to work except that some flow boards are not there anymore after the update.
Although I don't use $wgFlowOccupyPages, I also tried running the suggested update scripts:
php maintenance/populateContentModel.php --ns=all --table=page php extensions/Flow/maintenance/FlowUpdateRevContentModelFromOccupyPages.php
Attached is the output of php maintenance/update.php, at the end it says:
Completed Updated 1 workflows Failed: 5
and then it pretty-prints some data structure that look like they have something to do with the missing discussions.
What is a tiny bit scarry is that I only get this error message once, i.e. if I re-run update.php, there is no failure anymore so I'm worried that the update removes the data from the database :-/