Troubleshooting

Solutions to common or potentially confusing problems are documented here.

ASGI 'lifespan' protocol appears unsupported

Uvicorn 7.0+ outputs this if an exception occurred during application startup. You can make Uvicorn log the exception by passing --lifespan=on, e.g.:

uvicorn myproject.asgi:app --lifespan=on

In particular, this may occur if you use Bocadillo 0.14+ and did not call configure() before serving the application (see Configuration).