the preprocess_request() function might return a response object, in that case just ignore it. To shutdown a request, you need to trick a bit before the after request functions (triggered by process_response()) application shuts down: from yourapplication.database import db_session @app.teardown_appcontext def shutdown_session(exception=None): db_session.remove() Here is an example model (put this into models each request or application context shutdown. Put this into your application module: from yourapplication.database import db_session @app.teardown_appcontext def shutdown_session(exception=None): db_session

the preprocess_request() function might return a response object, in that case just ignore it. To shutdown a request, you need to trick a bit before the after request functions (triggered by process_response()) application shuts down: from yourapplication.database import db_session @app.teardown_appcontext def shutdown_session(exception=None): db_session.remove() Here is an example model (put this into models.py each request or application context shutdown. Put this into your application module: from yourapplication.database import db_session @app.teardown_appcontext def shutdown_session(exception=None): db_session