jgoedeke opened a new issue, #59551:
URL: https://github.com/apache/airflow/issues/59551
### Apache Airflow version
3.1.5
### If "Other Airflow 3 version" selected, which one?
_No response_
### What happened?
When using the HITLOperator, if a DAG param does not have an explicit
default value, DAG import fails with a ParamValidationError (previously this
worked). See error in logs:
```
[2025-12-16 16:44:52] ERROR - Failed to import:
/opt/airflow/dags/legacy_data_processing/mydag.py
ParamValidationError: Invalid input for param my_param: No value passed and
Param has no default value
File
"/home/airflow/.local/lib/python3.11/site-packages/airflow/models/dagbag.py",
line 405 in parse
File "<frozen importlib._bootstrap_external>", line 940 in exec_module
File "<frozen importlib._bootstrap>", line 241 in _call_with_frames_removed
File "/opt/airflow/dags/legacy_data_processing/mydag.py", line 438 in
<module>
File
"/home/airflow/.local/lib/python3.11/site-packages/airflow/sdk/definitions/dag.py",
line 1557 in factory
File "/opt/airflow/dags/legacy_data_processing/mydag.py", line 228 in mydag
File
"/home/airflow/.local/lib/python3.11/site-packages/airflow/sdk/bases/operator.py",
line 522 in apply_defaults
File
"/home/airflow/.local/lib/python3.11/site-packages/airflow/providers/standard/operators/hitl.py",
line 101 in __init__
File
"/home/airflow/.local/lib/python3.11/site-packages/airflow/providers/standard/operators/hitl.py",
line 121 in validate_params
File
"/home/airflow/.local/lib/python3.11/site-packages/airflow/sdk/definitions/param.py",
line 242 in validate
```
### What you think should happen instead?
Airflow should allow DAGs with params lacking explicit defaults to import,
as in earlier versions. This validation should not prevent import for
HITLOperator and similar uses.
### How to reproduce
1. Create a DAG with a HITLOperator and a param without a default (e.g.
params={"my_param": Param(type="string")})
2. Place the DAG in the dags folder for Airflow 3.1.5
3. Import will fail with ParamValidationError on the missing default value
4. This does not occur in older Airflow versions
### Operating System
Debian based, official docker image
### Versions of Apache Airflow Providers
_No response_
### Deployment
Other Docker-based deployment
### 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
- [x] I agree to follow this project's [Code of
Conduct](https://github.com/apache/airflow/blob/main/CODE_OF_CONDUCT.md)
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