Kind of stumped on this one. I have an asset with no upstream assets defined as follows:

@asset(
    partitions_def=MultiPartitionsDefinition(
        {
            "days": DailyPartitionsDefinition(
                start_date=datetime.strptime("2019-09-10", "%Y-%m-%d"),
                timezone="Etc/UTC",
                end_offset=-1,
            ),
            "dynamic_partitions_definition": futures_partitions["asset"],
        }
    )
)

where

"dynamic_partitions_definition"

points at a dict of `DynamicPartitionDefinition`s that are populated by another asset. When I try to backfill this asset in dagit, I get a popup that says "An unexpected error occurred. This backfill was not launched." with this error:

dagster._check.CheckError: Failure condition: upstream_partitions_subset must be a TimeWindowPartitionsSubset
  File "/home/wing/.cache/pypoetry/virtualenvs/syncdag-NSDSaiv4-py3.11/lib/python3.11/site-packages/dagster_graphql/implementation/utils.py", line 126, in _fn
    return fn(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^
  File "/home/wing/.cache/pypoetry/virtualenvs/syncdag-NSDSaiv4-py3.11/lib/python3.11/site-packages/dagster_graphql/implementation/utils.py", line 57, in _fn
    result = fn(self, graphene_info, *args, **kwargs)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/wing/.cache/pypoetry/virtualenvs/syncdag-NSDSaiv4-py3.11/lib/python3.11/site-packages/dagster_graphql/schema/roots/mutation.py", line 298, in mutate
    return create_and_launch_partition_backfill(graphene_info, backfillParams)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/wing/.cache/pypoetry/virtualenvs/syncdag-NSDSaiv4-py3.11/lib/python3.11/site-packages/dagster_graphql/implementation/execution/backfill.py", line 158, in create_and_launch_partition_backfill
    backfill = PartitionBackfill.from_asset_partitions(
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/wing/.cache/pypoetry/virtualenvs/syncdag-NSDSaiv4-py3.11/lib/python3.11/site-packages/dagster/_core/execution/backfill.py", line 325, in from_asset_partitions
    serialized_asset_backfill_data=AssetBackfillData.from_asset_partitions(
                                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/wing/.cache/pypoetry/virtualenvs/syncdag-NSDSaiv4-py3.11/lib/python3.11/site-packages/dagster/_core/execution/asset_backfill.py", line 234, in from_asset_partitions
    target_subset |= asset_graph.bfs_filter_subsets(
                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/wing/.cache/pypoetry/virtualenvs/syncdag-NSDSaiv4-py3.11/lib/python3.11/site-packages/dagster/_core/definitions/asset_graph.py", line 453, in bfs_filter_subsets
    partition_mapping.get_downstream_partitions_for_partitions(
  File "/home/wing/.cache/pypoetry/virtualenvs/syncdag-NSDSaiv4-py3.11/lib/python3.11/site-packages/dagster/_core/definitions/time_window_partition_mapping.py", line 131, in get_downstream_partitions_for_partitions
    check.failed("upstream_partitions_subset must be a TimeWindowPartitionsSubset")
  File "/home/wing/.cache/pypoetry/virtualenvs/syncdag-NSDSaiv4-py3.11/lib/python3.11/site-packages/dagster/_check/__init__.py", line 1669, in failed
    raise CheckError(f"Failure condition: {desc}")

hey @Drew You! are there any assets downstream of this asset? or is this just an isolated node?

you nailed it. it was the downstream asset causing it. My bad, the error message made me think that dagster thought there was something upstream of the backfill.

that's definitely a confusing error message blobl grimace