Bad Request. Required fields not supplied

[YaronN]

(The following is a response I've posted on January '25 and since have seen 26 'helpful' comments.
I'm creating it here with the exact title to make it easier to find.
Original post )

If anyone else encounters "Bad Request. Required fields not supplied" when trying to publish an action in Flow Designer, you might have stumbled on the issue I have found:

Opened Flow Designer and created/saved/published an action while in an Application Scope.
(Action is created as accessible from all scopes)
Later, accessed it, updated and tried to re-publish from the global scope - got : "Bad Request. Required fields not supplied" and action not published.

Resolution: Go back to the scope where action was originally created/published - action will be published correctly.