Webserver Crashing on Timeout During DAG Load

critical

reliabilityUpdated Apr 3, 2019

Webserver repeatedly crashes and restarts (503 errors) when DAG loading exceeds timeout threshold, preventing UI access even while scheduler and workers continue operating.

Sources

7 Common Errors to Check When Debugging Airflow DAGswww.astronomer.io

Technologies:

Apache AirflowThe root cause of this issue originates in Apache Airflow

airflow.webserver.response_time

airflow.webserver.requests.failed

airflow.dagbag.dag_processing.total_parse_time

How to detect:

Monitor for repeated webserver restarts, 503 HTTP errors, and webserver memory usage. Check if webserver logs show timeout errors during DAG parsing or initialization phase.

Recommended action:

Increase web_server_master_timeout and web_server_worker_timeout configuration; allocate more CPU/memory resources to webserver (minimum 5 AU / 0.5 CPU / 1.88 GiB); move heavy API calls and database queries inside operators rather than at DAG top-level; optimize DAG parsing performance.