Thanks! Clear steps to reproduce and providing the complete error message welcome. I assume this is about the frontpage https://phabricator.wikimedia.org/ ? If so, I can reproduce:

https://phabricator.wikimedia.org/feed/query/2HfUlTnoqZbw/

Unhandled Exception ("InvalidArgumentException")
Argument 1 passed to array_fuse() must be of the type array, boolean given, called in /srv/deployment/phabricator/deployment-cache/revs/7dd45143c333b8fb854b8f40bd96c46ea56a0970/phabricator/src/applications/search/field/PhabricatorSearchCheckboxesField.php on line 26 and defined

Another user @RobH reported this too a few weeks ago. This problem was caused by the feed being modernised.

Though i am unsure how to reproduce on phab-01 as it takes me to https://phab-01.wmflabs.org/feed/query/all/

but I'm guessing this is because someone updated the dashboard to only show recent activity for the tasks you've been in. When logged out it shows it for everyone.

@mmodell would you know how to fix this please?

I've created https://phabricator.wikimedia.org/D674 but it's untested as i can't reproduce locally.

Upstreamed:

• Task: https://secure.phabricator.com/T12851
• Patch: https://secure.phabricator.com/D18132