Flask 'RuntimeError: Working outside of application context.' when using current_app, g, or an extension in a script, test or at import time

Cause: current_app and g are proxies that only work while an application context is active. Flask pushes one automatically when handling a request and when running commands registered with @app.cli.command(). Code that runs at import time, in a plain script, in a background thread, or in a test without a client request has no context, so Flask raises "RuntimeError: Working outside of application context. This typically means that you attempted to use functionality that needed to interface with the current application object in some way. To solve this, set up an application context with app.app_context()." Fix (best first): 1. If you have the app object (script, test setup, app factory), push a context: with app.app_context(): init_db(). Everything inside the with block can use current_app and g. 2. If the code is not about configuring the app, move it into a view function or a CLI command, where the context is created for you, instead of running it at module level. 3. In tests, either use app.test_client() for requests, or call the function under test inside with app.app_context(): (use app.test_request_context() if it also needs request or session). 4. Avoid importing the app object into library modules (it causes circular imports); use current_app inside functions that run during a request or context instead. 5. For threads or background jobs, the same idea applies: give the worker the app object and push a context with app.app_context() inside it. 6. Remember that g only lives as long as the context; do not use it to store data between requests (use session or a database). Verify: re-run the script or test; the error is gone and current_app.config returns your configuration inside the block. Sources: https://flask.palletsprojects.com/en/stable/appcontext/ https://flask.palletsprojects.com/en/stable/testing/