In which file did you encounter the issue?

https://github.com/GoogleCloudPlatform/python-docs-samples/blob/9c71acbdf534defb400212ea68cf8359e3a3c4c3/composer/workflows/airflow_db_cleanup.py

Did you change the file? If so, how?

• "age_check_column": DagModel.last_scheduler_run,

• "age_check_column": DagModel.last_parsed_time,

Describe the issue

Starting from Airflow 2.0.2 last_scheduler_run column renamed into last_parsed_time in DagModel.
https://github.com/apache/airflow/blob/96656527fed515d8f39bbbec5d6a155faae2aaa2/CHANGELOG.txt#L369