Reraise exception in yield except block but get FastAPIError finally.

[seokhyuncheong1]

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Example Code

async def redis_session() -> AsyncGenerator[Redis, None]:
    async with RedisPool() as client:
        try:
            yield client
        except Exception:
            logger.warning(f'redis_session error: {traceback.format_exc()}')
            raise

Description

Hi, our teams are considering updating FastAPI to v0.110.1.
After update FastAPI to v0.110.1, we suffer due to FastAPIError.
we use yield object in logic, and reraise exception in except block like below code.

async def redis_session() -> AsyncGenerator[Redis, None]:
    async with RedisPool() as client:
        try:
            yield client
        except Exception:
            logger.warning(f'redis_session error: {traceback.format_exc()}')
            raise

We use redis session with Depends().
When we raise custom exception, fastapi return FastAPIError response and we can see below error msg.

No response object was returned. There's a high chance that the application code is raising an exception and a dependency with yield has a block with a bare except, or a block with except Exception, and is not raising the exception again. Read more about it in the docs:
https://fastapi.tiangolo.com/tutorial/dependencies/dependencies-with-yield/#dependencies-with-yield-and-except

We add custom_exception_handler to FastAPI and it is not working...
Also, we return JSONResponse in custom exception.
Please, give me some solutions...

Operating System

macOS

Operating System Details

No response

FastAPI Version

0.110.1

Pydantic Version

2.6.1

Python Version

3.11.8

Additional Context

No response

[konstantinos1981]

It seems you are re-raising an exception that was already caught. Try modifying the code to handle the exception within the block

async def redis_session() -> AsyncGenerator[Redis, None]:
    async with RedisPool() as client:
        try:
            yield client
        except Exception as e:
            logger.warning(f'redis_session error: {traceback.format_exc()}')
            raise e # Re-raise the caught exception

[YuriiMotov]

I tried to reproduce your issue, but I didn't succeed. Everything works fine.

Can you give a minimal working example that we can run and see that problem?

[YuriiMotov]

Closing this. Feel free to reopen it when you are ready to provide more info