airflow dag failed... but all tasks succeeded

Question

I am extremely confused by something in our airflow ui. In the tree view (and the graph view), a dag is indicated to have failed. However, all of its member tasks appear to have succeeded. You can see it here below (third from the end):

Does anyone know how this is possible, what it means, or how one would investigate it?

Answer 1

I have experienced the same. All tasks complete with success, but the DAG fails. Did not find anything in any logs.

In my case, it was the DAG's dagrun_timeout setting that was set too low for my tasks that did run for more than 30 minutes:

dag = DAG(...,
          dagrun_timeout=timedelta(minutes=30),
          ...)

I am on Airflow version 1.10.1.