Issue with Flask exception handler when running via gunicorn

[PavloPanchyshak]

Issue with Flask Exception Handler When Running via Gunicorn

Environment

• Python 3.11.2
• Gunicorn: 23.0.0
• Flask: 2.2.5
• Flask Extensions:
  • Flask-RESTx: 1.3.0
  • Flask-Cors: 4.0.0
  • Flask-Migrate: 4.0.7
  • Flask-Pydantic: 0.12.0
  • Flask-SocketIO: 5.5.1
  • Flask-SQLAlchemy: 3.1.1
  • Flask-SSE: 1.0.0

Problem Description

I have a Flask application with a global exception handler defined as follows:

@app.errorhandler(Exception)
def handle_generic_exception(error):
    traceback.print_exc()
    return Response(
        status=ExceptionType.GENERIC_EXCEPTION.http_status,
        mimetype='application/json',
        response=json.dumps({
            'error': ExceptionType.GENERIC_EXCEPTION.message,
        }),
    )

Additionally, I have a simple route that raises an exception:

@app.route("/")
def hello_world():
    raise Exception('Not Work')
    return json.dumps({"message": "Hello, World!"})

Expected Behavior

When running the application locally using:

app.run(host="0.0.0.0", port=8000, debug=settings.IS_LOCAL)

the exception handler works correctly, and a JSON response with the defined error message is returned.

Issue

However, when running the application via Gunicorn:

gunicorn -w 4 grade_wiz.grade_wiz:app --timeout 3600 --keep-alive 5 --log-level info --bind=0.0.0.0:8000

the @app.errorhandler(Exception) does not catch the exception, and a standard HTTP 500 response is returned instead.

Requested Help

How can I properly configure exception handling in Flask so the handler works correctly when running via Gunicorn?

Any advice or guidance on possible solutions would be greatly appreciated.