I found this bug when I was using django-rest-swagger, but during debugging I found out that the problem is in the DRF itself.

Checklist

• I have verified that that issue exists against the master branch of Django REST framework.
• I have searched for similar issues in both open and closed tickets and cannot find a duplicate.
• This is not a usage question. (Those should be directed to the discussion group instead.)
• This cannot be dealt with as a third party library. (We prefer new functionality to be in the form of third party libraries where possible.)
• I have reduced the issue to the simplest possible case.
• I have included a failing test as a pull request. (If you are unable to do so we can still accept the issue.)

Steps to reproduce

• Use a ViewSet with DRF permission class raising Http404, for instance DjangoObjectPermissions from rest_framework.permissions
• Install django-rest-swagger in your django project
• Go to the URL where swagger view is configured to be called

Expected behavior

The page loads and you can see all accessible endpoints.

Actual behavior

The page loads but you see message like this: "Can't read swagger JSON from http://localhost:8000/?format=openapi". When you check in the developer console you notice that this URL returned HTTP 404.