Gunicorn module path misconfiguration causes all routes to 404

Gunicorn started with wrong module:variable syntax fails to load Flask app. All routes return 404 because Flask defaults to 404 when app object not found. Works locally but fails after deployment.

Use correct Gunicorn syntax: 'gunicorn myapp.app:app' for direct app object, or 'gunicorn "myapp:create_app()"' for application factory. Verify variable name matches (app vs application).