In the previous Task Queue modules, it was possible to fail tasks in the queue by using a microflow action. This was useful so that the task would enter the retry mechanism. This is especially useful when processing an interface response should cause a retry. In message handling, it is not always possible to end with an error event. In the new native Mendix Task Queue, this doesn't seem to be possible.
The current workaround is to use ThrowException or create a variable in which you divide by 0. If the platform does not support this now, then a new action in the toolkit would be very welcome. Another option would be to return a boolean for scheduled tasks (true = success, false = failed).
https://community.mendix.com/link/space/usability/questions/132081