DAG import error after v3 upgrade #56306

Hi community,

I run into the same error after Airflow was upgraded to version 3, and worked around it by updating the dag_id parameter with a different value. I did delete all entries in serialized_dag table but not dag_code table. I guess both ways may trigger the same logic in the codes to work around the error. Just to see if someone happens to know the cause.

Is there a way to fix this manually?

airflow db migrate was failing (no dag_id in the dag_code table). I ended up deleting rows in the dag_code and serialized_dag tables but now my DAG processor has these errors:

    latest_ser_dag._data = new_serialized_dag._data
    ^^^^^^^^^^^^^^^^^^^^
AttributeError: 'NoneType' object has no attribute '_data'

I tried entering the dag processor pod and running airflow dags reserialize but no luck.

If you have access to DB, truncate dag_code and serialized_dag table.

Originally posted by @kaxil in #49563 (comment)