Comment 2 for bug 1970557

I'm also encountering this issue, I probed a bit and noticed that the issue seems to be related to a mismatch between the fastapi version that is shipped in Ubuntu (0.63.0) and the starlette version (0.18.0).

As of changelog, officially fastapi started supporting starlette 0.18.0 only as of 0.76.0 (i.e. here https://fastapi.tiangolo.com/release-notes/#0760). For fastapi 0.63.0 the starlette requirement is 0.13.6 (i.e. here https://github.com/tiangolo/fastapi/blob/0.63.0/pyproject.toml#L35)

There also seem to be issues with uvicorn, for example fastapi 0.63.0 depends on uvicorn between 0.12.0 and 0.14.0 (i.e. here https://github.com/tiangolo/fastapi/blob/0.63.0/pyproject.toml#L93) but the system installed version is 0.15.0.

Bumping fastapi to a newer version should fix the package, as the bug above it can't really be used right now