LatestOnlyOperator not working if just before a Dynamic Task Mapping

Apache Airflow version

Other Airflow 3 version (please specify below)

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

3.1.5

What happened?

When backfilling a DAG with LatestOnlyOperator, I realised the tasks after the LatestOnlyOperator were still executing.

I think it used to work before (probably in 2.*) but can't confirm that anymore.

What you think should happen instead?

When backfilling (before the current schedule), the tasks following the LatestOnlyOperator should be skipped, as per the purpose of this operator.

How to reproduce

The following stripped-down code reproduces the problem in my environment, when I backfill a few days before the current day:

for the test_bug_OK DAG, intermediate_step and print_all tasks are skipped
for the test_bug_KO DAG, print_all tasks still execute

from airflow.providers.standard.operators.latest_only import LatestOnlyOperator
from airflow.sdk import DAG, task
from pendulum import datetime

with DAG(
    dag_id="test_bug_KO",
    schedule="0 1 * * *",
    start_date=datetime(2026, 1, 1),
    catchup=False,
):
    is_latest = LatestOnlyOperator(task_id="is_latest")

    @task
    def print_label(label: str):
        print(label)

    print_all = print_label.expand(label=["Label 0", "Label 1"])

    is_latest >> print_all


with DAG(
    dag_id="test_bug_OK",
    schedule="0 1 * * *",
    start_date=datetime(2026, 1, 1),
    catchup=False,
):
    is_latest = LatestOnlyOperator(task_id="is_latest")

    @task
    def print_label(label: str):
        print(label)


    intermediate_step = print_label("Before")

    print_all = print_label.expand(label=["Label 0", "Label 1"])

    is_latest >> intermediate_step >> print_all

Operating System

Debian 13.3

Versions of Apache Airflow Providers

apache-airflow-providers-amazon==9.18.0
apache-airflow-providers-common-compat==1.10.0
apache-airflow-providers-common-io==1.7.0
apache-airflow-providers-common-sql==1.30.0
apache-airflow-providers-fab==3.0.1
apache-airflow-providers-http==5.6.0
apache-airflow-providers-postgres==6.5.0
apache-airflow-providers-samba==4.12.0
apache-airflow-providers-smtp==2.4.0
apache-airflow-providers-ssh==4.1.5
apache-airflow-providers-standard==1.10.0

Deployment

Virtualenv installation

Deployment details

No response

Anything else?

The problem recurs every time

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

It seems when the LatestOnlyOperator is a not dynamic then map_index of -1 is passed to downstream tasks. In case of dynamic tasks being dependent on LatestOnlyOperator it will try to skip -1 which will not exist but in case of normal dependent then -1 will be correct and as it's marked skipped the downstream though dynamic is also marked as skipped.

[2026-02-18 17:42:54] INFO - Checking latest only with left_window: 2026-01-03 01:00:00+00:00 right_window: 2026-01-05 01:00:00+00:00 now: 2026-02-18 12:12:54.160606+00:00
[2026-02-18 17:42:54] INFO - Not latest execution, skipping downstream.
[2026-02-18 17:42:54] INFO - Branch into []
[2026-02-18 17:42:54] INFO - Following branch set()
[2026-02-18 17:42:54] INFO - Skipping tasks [('print_label', -1)]

airflow/providers/standard/src/airflow/providers/standard/utils/skipmixin.py

Lines 180 to 185 in 0d3a034

    
           skip_tasks = [ 
        
               (t.task_id, ti.map_index) for t in downstream_tasks if t.task_id not in branch_task_id_set 
        
           ] 
        
           follow_task_ids = [t.task_id for t in downstream_tasks if t.task_id in branch_task_id_set] 
        
           log.info("Skipping tasks %s", skip_tasks)

fix: use parent's map_index for XCom lookup in NotPreviouslySkippedDep

fix: `LatestOnlyOperator` not working if direct upstream of Dynamic T…

[v3-1-test] fix: `LatestOnlyOperator` not working if direct upstream …

fix: `LatestOnlyOperator` not working if direct upstream of Dynamic T…

[v3-1-test] fix: `LatestOnlyOperator` not working if direct upstream …

fix: `LatestOnlyOperator` not working if direct upstream of Dynamic T…

[v3-1-test] fix: `LatestOnlyOperator` not working if direct upstream …

fix: `LatestOnlyOperator` not working if direct upstream of Dynamic T…

Navigation Menu

Repository navigation

LatestOnlyOperator not working if just before a Dynamic Task Mapping #62118

Apache Airflow version

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

What happened?

What you think should happen instead?

How to reproduce

Operating System

Versions of Apache Airflow Providers

Deployment

Deployment details

Anything else?

Are you willing to submit PR?

Code of Conduct

Metadata

Assignees

Labels

Type

Projects

Milestone

Relationships

Development

	skip_tasks = [
	(t.task_id, ti.map_index) for t in downstream_tasks if t.task_id not in branch_task_id_set
	]

	follow_task_ids = [t.task_id for t in downstream_tasks if t.task_id in branch_task_id_set]
	log.info("Skipping tasks %s", skip_tasks)

LatestOnlyOperator not working if just before a Dynamic Task Mapping #62118

Description

Apache Airflow version

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

What happened?

What you think should happen instead?

How to reproduce

Operating System

Versions of Apache Airflow Providers

Deployment

Deployment details

Anything else?

Are you willing to submit PR?

Code of Conduct

Activity

tirkarthi commented on Feb 18, 2026

Metadata

Metadata

Assignees

Labels

Type

Projects

Milestone

Relationships

Development

Issue actions