Apache Airflow version

main (development)

If "Other Airflow 3 version" selected, which one?

No response

What happened?

When a deferrable sensor with soft_fail=True times out, the task fails with AirflowSensorTimeout instead of being marked as SKIPPED. This is a regression from Airflow 2.x where the same configuration correctly skipped the task and downstream tasks.

Actual behavior in Airflow 3.x:

• Task state: FAILED
• Error: AirflowSensorTimeout: Trigger timeout
• Log shows: TaskDeferralTimeout: Trigger timeout in BaseSensorOperator.resume_execution()
• Downstream tasks: Not executed

Workaround: Setting deferrable=False forces the sensor to use traditional poke mode, which correctly respects soft_fail=True on timeout.

What you think should happen instead?

A sensor configured with soft_fail=True should be marked as SKIPPED when it times out, regardless of whether it's running in deferrable mode or traditional poke mode. The soft_fail parameter should work consistently across all sensor modes.

Expected behavior (works in Airflow 2.x):

• Task state: SKIPPED
• Downstream tasks: SKIPPED (according to trigger rules)
• No AirflowSensorTimeout exception raised

How to reproduce

from datetime import datetime, timedelta
from airflow.providers.standard.sensors.time_delta import TimeDeltaSensor
from airflow.providers.standard.operators.empty import EmptyOperator
from airflow.sdk import DAG

with DAG(
    dag_id='test_sensor_soft_fail',
    start_date=datetime(2024, 1, 1),
    schedule=None,
) as dag:
    # Sensor waiting for 1 hour but will timeout after 10 seconds
    sensor = TimeDeltaSensor(
        task_id='test_timedelta_sensor',
        delta=timedelta(hours=1),  # Wait for 1 hour
        timeout=10,  # But timeout after 10 seconds
        soft_fail=True,  # Should skip on timeout
        deferrable=True,  # Use deferrable mode
    )

    downstream = EmptyOperator(task_id='downstream_task')

    sensor >> downstream

Steps:

1. Run the DAG with deferrable=True (as shown above)
2. Wait for sensor to timeout after 10 seconds
3. Observe task FAILS with AirflowSensorTimeout and downstream task is not executed
4. Change deferrable=True to deferrable=False in the sensor configuration
5. Run the DAG again with deferrable=False
6. Wait for sensor to timeout after 10 seconds
7. Observe task is marked as SKIPPED and downstream task is also skipped (correct behavior)

Expected behavior (Airflow 2.x): Task skips on timeout regardless of deferrable mode
Actual behavior (Airflow 3.x):

• With deferrable=True: Task FAILS on timeout
• With deferrable=False: Task SKIPS on timeout (correct)

Operating System

Debian GNU/Linux 12 (bookworm)

Versions of Apache Airflow Providers

No response

Deployment

Official Apache Airflow Helm Chart

Deployment details

No response

Anything else?

No response

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