Uvicorn fails "quietly" upon a circular import error

[mikeedjones]

From this comment and discussion.

When there is a circular import in the app, uvicorn reports ERROR: Error loading ASGI app. Could not import module "main". without exposing the stacktrace which would be reported if you ran the code using python main.py. MRE below.

# main.py
from bar import Bar

class Foo:
    pass

async def app(scope, receive, send):
    assert scope['type'] == 'http'

#bar.py
from main import Foo

class Bar:
    pass

Running with

uvicorn main:app

only results in

ERROR:    Error loading ASGI app. Could not import module "main".

whereas running

python main.py

reports the far more useful

ImportError: cannot import name 'Bar' from partially initialized module 'bar' (most likely due to a circular import) (/workspaces/fastapi/bar.py)

Not sure how you'd start debugging this one I'm afraid - or if its even a "bug". For comparison syntax errors are reported correctly.

[Kludex]

Thanks.

#2035

[Markundi]

Hello,

Could you please suggest me on this ( Kafka FAST API)

##########main.py ################################
from fastapi import FastAPI

app = FastAPI()

@app.get("/")
async def root():
return {"message": "Hello World"}

---

error :
C:\Users\Satish\microservice-kafka-project\ms_01>docker compose logs api -f
ms_01 | Skipping virtualenv creation, as specified in config file.
ms_01 | INFO: Will watch for changes in these directories: ['/code']
ms_01 | INFO: Uvicorn running on http://0.0.0.0:8000 (Press CTRL+C to quit)
ms_01 | INFO: Started reloader process [1] using StatReload
ms_01 | ERROR: Error loading ASGI app. Could not import module "ms_01.main".