I am running into this failure state message:

Failed: At least one upstream state has an unmappable result.

It first came about after I included a switch statement that chooses between a mapped task, or a normal task that returns an iterable. For example:

with case(use_map, True):
    results = some_task.map(inputs) # some_task returns mapped results

with case(use_map, False):
    results = manual_mapping_task(inputs) # manual_mapping_task returns python iterable in its results

downstream_task(results) # "Failed: At least one upstream state has an unmappable result"

Is this a valid use of "results" in the downstream task? Is it possible this is where my error is coming from?

Hi Lewis, I'm unable to replicate, can you provide an example that fails in the same way (using simple tasks).

I'm sorry, it appears I was using a reserved keyword for an argument to the downstream task and it just so happened to show up at the same time I included the switch.