Backwards backfill UI incorrectly shows “no running tasks” while older backfill task instances are still running #64827

Under which category would you file this issue?

Airflow Core

Apache Airflow version

airflow:3.1.7

What happened and how to reproduce it?

What happened?

During a backwards backfill, the Airflow UI main page indicates that there are no running tasks, even though at least one task instance is still running.

From what I can see, this happens when the most recent/latest task instance is already in a completed state, while an older task instance is still running. The UI appears to infer that nothing is running based on the latest task, instead of checking whether any task instance in the backfill is still running.

What you think should happen instead?

The UI should report running tasks whenever any task instance in the relevant backfill / DAG run is still running.

Operating System

airflow@airflow-dev-api-server-55ff78f868-pfb2s:/opt/airflow$ cat /etc/os-release PRETTY_NAME="Debian GNU/Linux 12 (bookworm)" NAME="Debian GNU/Linux" VERSION_ID="12" VERSION="12 (bookworm)" VERSION_CODENAME=bookworm ID=debian HOME_URL="https://www.debian.org/" SUPPORT_URL="https://www.debian.org/support" BUG_REPORT_URL="https://bugs.debian.org/"

Deployment

Official Apache Airflow Helm Chart

Apache Airflow Provider(s)

No response

Versions of Apache Airflow Providers

No response

Official Helm Chart version

1.19.0

Kubernetes Version

v1.33.9

Helm Chart configuration

No response

Docker Image customizations

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