add_middleware causes exceptions to not be raised/handled silently

[fraser-langton]

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Example Code

import uvicorn
from fastapi import FastAPI
from starlette.middleware.base import BaseHTTPMiddleware


app = FastAPI()


@app.get("/info")
def info():
    # raises Exception as expected, the traceback is seen in console
    raise Exception


private_api = FastAPI()


@private_api.get("/info")
def info():
    # exception is handled silently, no traceback is seen in console
    raise Exception


app.mount("/private", private_api)


class Middleware(BaseHTTPMiddleware):

    async def dispatch(self, request, call_next):
        return await call_next(request)


app.add_middleware(Middleware)  # when this is removed, the exceptions are raised for all routes


if __name__ == '__main__':
    uvicorn.run(app, port=8000)

Description

When exceptions are raised on a subapp, the exceptions are not propagated all the way to see in console
In the example code
/info raises an exception and the full stacktrace is seen in console
/private/info does not raise the exception and only INFO: 127.0.0.1:56308 - "GET /info HTTP/1.1" 500 Internal Server Error is shown in console

Operating System

Windows

Operating System Details

No response

FastAPI Version

0.74.0

Python Version

3.8.10

Additional Context

uvicorn==0.17.6

[fraser-langton]

Upgrading to 0.79.0 the issue goes away, not sure if this was fixed intentionally (I couldn't find a closed issue) or inadvertently in which case might still be an issue elsewhere

[iudeen]

What's the behavior if you add the Middleware to both of your apps? 🤔

[Kludex]

Upgrading to 0.79.0 the issue goes away, not sure if this was fixed intentionally (I couldn't find a closed issue) or inadvertently in which case might still be an issue elsewhere

It was solved on Starlette.

[fraser-langton]

It was solved on Starlette.
Thanks @Kludex - was very confused!

[fraser-langton]

Issue is back see my versions below, should I open an issue on starlette?

fastapi==0.88.0
starlette==0.23.0
uvicorn==0.20.0

[Kludex]

You can open a discussion on starlette.

[fraser-langton]

Opened discussion in starlette