Airflow “This DAG isnt available in the webserver DagBag object ” - airflow

I am currently setup airflow scheduler in Linux server A and airflow web server in Linux server B. Both server has no Internet access. I have start the initDB in server A and keep all the dags in server A.
However, when i refresh the webserver UI, it keep having error message:-
This DAG isn't available in the webserver DagBag object
How do i configure the dag folder for web server (server B) to read the dag from scheduler (server A)?
I am using bashoperator. Is that Celery Operator is a must?
Thanks in advance

The scheduler has found your dags_folder, and its processes, and is scheduling them accordingly. The webserver however can "see" these processes solely by their existence in the database but can't find them in its dags_folder path.
You need to ensure that the dags_folder for both servers contain the same files, and that both are kept in sync with one another. This is out of scope for Airflow and it won't handle this on your behalf.

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