airflow dags test fails with AttributeError: 'dict' object has no attribute 'hex' for DAGs with deadline

[wislertt]

Apache Airflow version

3.3.2 (latest). I reproduced the bug with the DAG below on 3.3.1 and 3.3.2. The same code is also present on main.

What happened?

Running airflow dags test on a DAG that sets deadline=DeadlineAlert(...) completes the run successfully (tasks succeed, DagRun is marked success), then crashes with a traceback during the final DagRun.update_state() call:

Traceback (most recent call last):
  ...
  File "airflow/cli/commands/dag_command.py", line 834, in dag_test
    dr: DagRun = dag.test(...)
  File "airflow/sdk/definitions/dag.py", line 1397, in test
    schedulable_tis, _ = dr.update_state(session=session)
  File "airflow/models/dagrun.py", line 1270, in update_state
    DeadlineAlertModel.get_by_id(alert_id, session=session) for alert_id in dag.deadline
  File "airflow/models/deadline_alert.py", line 115, in get_by_id
    result = session.scalar(select(cls).where(cls.id == deadline_alert_id))
  ...
  File "sqlalchemy/sql/sqltypes.py", line 3738, in process
    value = value.hex
AttributeError: 'dict' object has no attribute 'hex'

The exit code is non-zero, so the command reports failure for a run that actually succeeded.

Root cause

DAG.test() builds its "scheduler DAG" with an in-memory serialization round trip:

scheduler_dag = DagSerialization.deserialize_dag(DagSerialization.serialize_dag(self))

(airflow/sdk/definitions/dag.py, DAG.test())

Serialization encodes deadline alerts as plain dicts:

serialized_dag["deadline"] = [encode_deadline_alert(d) for d in dag.deadline]

(airflow/serialization/serialized_objects.py, around line 1742)

but deserialization stores the field back without decoding it:

dag.deadline = encoded_dag.get("deadline")

(airflow/serialization/serialized_objects.py, around line 1889)

So scheduler_dag.deadline is a list of encoded alert dicts.

When the run then succeeds, DagRun.update_state() prunes deadlines that are no longer needed:

deadline_alerts = [
    DeadlineAlertModel.get_by_id(alert_id, session=session) for alert_id in dag.deadline
]

(airflow/models/dagrun.py, around line 1270; same code around line 1371 on main)

get_by_id expects str | UUID, but each element here is an encoded alert dict, so SQLAlchemy's Uuid bind processor fails on value.hex.

The regular DB write path does not hit this because SerializedDagModel._generate_deadline_uuids (airflow/models/serialized_dag.py, around line 403) rewrites the serialized deadline field from alert dicts into a list of deadline_alert UUID strings before persisting. The in-memory round trip in DAG.test() bypasses that conversion.

How to reproduce

Save as deadline_dagtest_repro.py and run airflow dags test deadline_dagtest_repro. Tested as-is on 3.3.1 and 3.3.2.

from datetime import timedelta

from airflow.providers.standard.operators.empty import EmptyOperator
from airflow.sdk import DAG
from airflow.sdk.definitions.callback import SyncCallback
from airflow.sdk.definitions.deadline import DeadlineAlert, DeadlineReference


def _cb(**kwargs):
    pass


with DAG(
    dag_id="deadline_dagtest_repro",
    schedule=None,
    deadline=DeadlineAlert(
        reference=DeadlineReference.DAGRUN_LOGICAL_DATE,
        interval=timedelta(hours=2),
        callback=SyncCallback(_cb),
    ),
):
    EmptyOperator(task_id="task")

The task succeeds and the DagRun is marked success, then the traceback above is raised and the CLI exits with a non-zero code.

What you think should happen instead?

airflow dags test should complete cleanly (exit code 0) for DAGs with deadlines. Some possible fixes:

1. Decode the deadline entries in deserialize_dag so dag.deadline holds proper objects, matching how other serialized fields are decoded, or
2. Make the deadline pruning block in DagRun.update_state() tolerant of both shapes (encoded dicts and UUID strings), or
3. Apply the same dict-to-UUID conversion that write_dag performs inside the DAG.test() round trip (though no DB rows exist in the test path, so 1 or 2 is probably cleaner).

Anything else?

• The scheduler is not affected, since it consumes the persisted serialized DAG whose deadline field is already a list of UUID strings.
• Existing deadline PRs (Fix backward compatibility for deadline alert serialization #63701, Fix: allow deadline alert UUID references in serialized Dag schema #68195, allow deadline alert UUID references in serialized Dag schema #70148, Fix Dags with deadlines failing to parse after a database retry #71628) all touch the DB write path. None of them address the in-memory round trip in DAG.test().

Operating System

macOS (Darwin), Python 3.12 and 3.14. Not OS specific.

Versions of Apache Airflow Providers

apache-airflow-providers-standard (installed from the constraints file of each release).

Deployment

Virtualenv install, local CLI testing. Not deployment specific.

Are you willing to submit PR?

• Yes I am willing to submit a PR!

Code of Conduct

• I agree to follow this project's Code of Conduct.

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