carlinix opened a new issue, #59316:
URL: https://github.com/apache/airflow/issues/59316
### Apache Airflow version
3.1.4
### If "Other Airflow 2/3 version" selected, which one?
_No response_
### What happened?
In Airflow 3.1.4, when attempting to clear task instances using the UI —
specifically clearing upstream or downstream tasks — the operation fails and
returns a 500 Internal Server Error from the endpoint:
```
POST /api/v2/dags/<dag_id>/clearTaskInstances
```
## **Actual Behavior**
The API returns **500 Internal Server Error**, and the logs show a
`NotMapped` exception inside the mapped-operator traversal logic.
Excerpt from logs:
```
airflow.exceptions.NotMapped
```
Stack trace points to:
```
File "airflow/models/taskinstance.py", line 2288, in find_relevant_relatives
_visit_relevant_relatives_for_mapped(mapped_tasks)
File "airflow/models/mappedoperator.py", line 507
raise NotMapped()
```
Airflow incorrectly tries to call:
```
get_mapped_ti_count()
```
on a task that is **not** mapped, which triggers the exception.
---
## **Relevant Logs (Simplified)**
```
POST /api/v2/dags/<dag_id>/clearTaskInstances → 500
File "airflow/models/mappedoperator.py", line 507
raise NotMapped()
airflow.exceptions.NotMapped
```
Full error path shows the failure originates inside:
```
/airflow/api_fastapi/core_api/routes/public/task_instances.py
```
while handling:
```
find_relevant_relatives()
```
---
## **Analysis / Root Cause Hypothesis**
`find_relevant_relatives()` always attempts to evaluate mapped-task
relatives, even when the operator is **not mapped**.
The expected logic should be:
```python
if not task.is_mapped:
skip mapped-task processing
```
Instead, it directly calls:
```
_visit_relevant_relatives_for_mapped(...)
```
which then calls:
```
get_mapped_ti_count(...)
```
that raises `NotMapped()` when `task.is_mapped` is False.
This results in the 500 error.
---
## **Impact**
* Upstream/downstream clearing is **completely broken** in Airflow 3.1.4.
* UI recovery actions cannot be performed when DAGs are stuck or partially
executed.
* Manual database manipulation becomes the only workaround, which is unsafe
for production environments.
---
## **Possible Fix ?**
Add a guard condition before invoking mapped-task logic:
```python
if not task.is_mapped:
return
```
Specifically inside:
```
find_relevant_relatives()
```
or
```
_visit_relevant_relatives_for_mapped()
```
---
### What you think should happen instead?
Airflow should:
* Successfully clear the selected task instances.
* Apply upstream/downstream rules correctly.
* Return HTTP 200 OK.
Not attempt mapped-task logic on tasks that are not mapped.
### How to reproduce
1. Open the Airflow UI.
1. Navigate to any DAG.
1. Open a DAG Run.
1. Select a task, then choose Clear → Upstream or Downstream.
1. The UI does nothing and the backend returns a 500 error.
### Operating System
Ubuntu 24.04.3 LTS
### Versions of Apache Airflow Providers
```
Providers info
airflow-provider-duckdb | 0.2.0
apache-airflow-providers-amazon | 9.18.0
apache-airflow-providers-celery | 3.14.0
apache-airflow-providers-cncf-kubernetes | 10.11.0
apache-airflow-providers-common-compat | 1.10.0
apache-airflow-providers-common-io | 1.7.0
apache-airflow-providers-common-messaging | 2.0.1
apache-airflow-providers-common-sql | 1.30.0
apache-airflow-providers-docker | 4.5.0
apache-airflow-providers-elasticsearch | 6.4.0
apache-airflow-providers-fab | 3.0.3
apache-airflow-providers-ftp | 3.14.0
apache-airflow-providers-git | 0.1.0
apache-airflow-providers-google | 19.1.0
apache-airflow-providers-grpc | 3.9.0
apache-airflow-providers-hashicorp | 4.4.0
apache-airflow-providers-http | 5.6.0
apache-airflow-providers-microsoft-azure | 12.9.0
apache-airflow-providers-mysql | 6.4.0
apache-airflow-providers-odbc | 4.11.0
apache-airflow-providers-openlineage | 2.9.0
apache-airflow-providers-postgres | 6.5.0
apache-airflow-providers-redis | 4.4.0
apache-airflow-providers-salesforce | 5.12.0
apache-airflow-providers-sendgrid | 4.2.0
apache-airflow-providers-sftp | 5.5.0
apache-airflow-providers-slack | 9.6.0
apache-airflow-providers-smtp | 2.4.0
apache-airflow-providers-snowflake | 6.7.0
apache-airflow-providers-ssh | 4.2.0
apache-airflow-providers-standard | 1.10.0
```
### Deployment
Docker-Compose
### Deployment details
```
Apache Airflow
version | 3.1.4
executor | CeleryExecutor
task_logging_handler | airflow.utils.log.file_task_handler.FileTaskHandler
sql_alchemy_conn |
postgresql+psycopg2://airflow:airflow@postgres/airflow
dags_folder | /opt/airflow/dags
plugins_folder | /opt/airflow/plugins
base_log_folder | /opt/airflow/logs
remote_base_log_folder |
```
```
System info
OS | Linux
architecture | x86_64
uname | uname_result(system='Linux', node='02adf0a80285',
release='6.14.0-36-generic', version='#36~24.04.1-Ubuntu SMP PREEMPT_DYNAMIC
Wed Oct 15 15:45:17 UTC 2', machine='x86_64')
locale | ('C', 'UTF-8')
python_version | 3.12.12 (main, Dec 10 2025, 07:42:02) [GCC 12.2.0]
python_location | /usr/python/bin/python3.12
```
```
Tools info
git | git version 2.39.5
ssh | OpenSSH_9.2p1 Debian-2+deb12u7, OpenSSL 3.0.17 1 Jul 2025
kubectl | NOT AVAILABLE
gcloud | NOT AVAILABLE
cloud_sql_proxy | NOT AVAILABLE
mysql | mysql Ver 15.1 Distrib 10.11.15-MariaDB, for
debian-linux-gnu (x86_64) using EditLine wrapper
sqlite3 | 3.40.1 2022-12-28 14:03:47
df5c253c0b3dd24916e4ec7cf77d3db5294cc9fd45ae7b9c5e82ad8197f3alt1
psql | psql (PostgreSQL) 18.1 (Debian 18.1-1.pgdg12+2)
```
```
Paths info
airflow_home | /opt/airflow
system_path |
/root/bin:/home/airflow/.local/bin:/usr/python/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
python_path |
/home/airflow/.local/bin:/opt/airflow/dags:/usr/python/lib/python312.zip:/usr/python/lib/python3.12:/usr/python/lib/python3.12/lib-dynload:/home/airflow/.local/lib/python3.12/site-packages:/usr/python/lib/python3.12/site-packages:/opt/airflow/confi
| g:/opt/airflow/plugins
airflow_on_path | True
```
### Anything else?
_No response_
### Are you willing to submit PR?
- [x] Yes I am willing to submit a PR!
### Code of Conduct
- [x] I agree to follow this project's [Code of
Conduct](https://github.com/apache/airflow/blob/main/CODE_OF_CONDUCT.md)
--
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.
To unsubscribe, e-mail: [email protected]
For queries about this service, please contact Infrastructure at:
[email protected]
