DAG not visible in Web-UI

I have the same issue. To resolve I need to run scheduler

airflow scheduler

Without this command, I don't see my new DAGs BTW: the UI show me warning related to that problem:

The scheduler does not appear to be running. Last heartbeat was received 9 seconds ago. The DAGs list may not update, and new tasks will not be scheduled.

We need to clarify several things:

1. By no means you need to run the DAG file yourself (unless you're testing it for syntax errors). This is the job of Scheduler/Executor.
2. For DAG file to be visible by Scheduler (and consequently, Webserver), you need to add it to dags_folder (specified in airflow.cfg. By default it's $AIRFLOW_HOME/dags subfolder).

Airflow Scheduler checks dags_folder for new DAG files every 5 minutes by default (governed by dag_dir_list_interval in airflow.cfg). So if you just added a new file, you have two options:

1. Restart Scheduler
2. Wait until current Scheduler process picks up new DAGs.

Run airflow list_dags to check, whether the dag file is located correctly.

For some reason, I didn't see my dag in the browser UI before I executed this. Must be issue with browser cache or something.

If that doesn't work, you should just restart the webserver with airflow webserver -p 8080 -D