async process_exception being called as sync from async view/middleware

[Gabriel Rado]

following this bold part from ​https://docs.djangoproject.com/en/4.1/topics/http/middleware/#asynchronous-support:

process_view, process_template_response and process_exception methods, if they are provided, should also be adapted to match the sync/async mode. However, Django will individually adapt them as required if you do not, at an additional performance penalty.

I'm using this middleware to parse errors from sync and async views:

@sync_and_async_middleware
def custom_error(get_response):
    if asyncio.iscoroutinefunction(get_response):

        async def middleware(request):
            response = await get_response(request)
            return response

        async def _process_exception(request, exception):
            return my_custom_process_exception(exception)

    else:

        def middleware(request):
            response = get_response(request)
            return response

        def _process_exception(request, exception):
            return my_custom_process_exception(exception)

    middleware.process_exception = _process_exception
    return middleware

and I'm getting "ValueError: The view my_view.view_func didn't return an HttpResponse object. It returned an unawaited coroutine instead. You may need to add an 'await' into your view." from ​https://github.com/django/django/blob/main/django/core/handlers/base.py#L257

i thought that with an async middleware + async view, all my hooks (process_view, process_template_response and process_exception) should be also async, but it appears that is mandatory to use sync process_exception with async capable middlewares. if this is intended, could the official docs be changed to expose this mandatory behavior?

[Carlton Gibson]

Hi Gabriel. OK, seems right, are you happy to suggest a docs adjustment? (… but if you could add a test to demonstrate what you're seeing explicitly, that would be good too.) Thanks.

[Gabriel Rado]

i tried to create a test to demonstrate this behavior and every try was successfull. thinking the problem could be another point of my project and not django itself, i'll close this ticket

[Carlton Gibson]

OK, thanks for the follow-up. Do reopen if you're able to reduce it to an issue in Django.