Sqlalchemy 2 migration - Fix MyPy type errors in core Airflow

[vincbeck]

Apache Airflow version

3.1.0

If "Other Airflow 2/3 version" selected, which one?

No response

What happened?

Summary

This issue tracks the resolution of MyPy type errors found in the Airflow core codebase when SQLA 2 is used.
There are currently 525 errors across 100 files that need to be addressed before being able to upgrade to SQLA2.
Also, this will improve type safety and code quality.

How to generate the errors

• Apply changes from Remove SQLA 1 limit in Fab provider #56212 locally

• Run breeze ci-image build --python 3.10 --upgrade-to-newer-dependencies

• Run prek --color always --verbose --hook-stage manual "mypy-airflow-core" --all-files reveals numerous type errors throughout the codebase. These errors primarily involve:

  • Incompatible type assignments (datetime vs UtcDateTime)
  • Missing type annotations
  • Union type handling issues
  • SQLAlchemy ORM type mismatches
  • Return value type inconsistencies

Current Status (Updated: 2025-11-24)

Total errors found: 24 errors in 8 files (checked 1021 source files)

Error Breakdown by Directory

airflow-core/src/airflow/models/ (13 errors in 4 files)

• connection.py (1 error)
• taskmap.py (4 errors)
• dag.py (2 errors)
• serialized_dag.py (6 errors)

airflow-core/src/airflow/ti_deps/deps/ (10 errors in 1 file)

• trigger_rule_dep.py (10 errors)

airflow-core/src/airflow/api_fastapi/common/db/ (1 error in 1 file)

• dag_runs.py (1 error)

airflow-core/src/airflow/api_fastapi/execution_api/routes/ (2 errors in 1 file)

• task_instances.py (2 errors)

airflow-core/src/airflow/api_fastapi/core_api/routes/ui/ (1 error in 1 file)

• dags.py (1 error)

How to Contribute

1. Pick a file: Choose an unchecked file from the list above
2. Check the box: Update this issue to mark the file as being worked on
3. Run MyPy locally: Follow the steps mentioned above to generate the errors. You can also run prek mypy-airflow-core --directory <directory> to run mypy in the directory you are working on
4. Fix the errors: Address the type errors in your chosen file
5. Test your changes: Ensure tests still pass
6. Submit a PR: Create a pull request with your fixes. Please do not include in your PR changes from Remove SQLA 1 limit in Fab provider #56212

Guidelines

• Focus on one file or directory at a time
• Follow existing code patterns and conventions

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Let's work together to improve Airflow's type safety! 🚀

Note: This issue was generated by running MyPy on the current codebase. The error counts may change as the codebase evolves.

What you think should happen instead?

No response

How to reproduce

• Apply changes from Remove SQLA 1 limit in Fab provider #56212 locally
• Run breeze ci-image build --python 3.10 --upgrade-to-newer-dependencies
• Run prek --color always --verbose --hook-stage manual "mypy-airflow-core" --all-files reveals numerous type errors throughout the codebase

Operating System

Macos

Versions of Apache Airflow Providers

No response

Deployment

Other

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