Google Cloud Debugger on Cloud Run Django "No code found at line..."

When trying to debug a Cloud Run Django application (Python 3.9) I get the

No code found at line 30 in /app/djangotest/

error. I looked at the docker image and the file seems to be in the right place, with debuggable code at the correct location:

    29  class UserViewSet(viewsets.ModelViewSet):
    30      queryset = User.objects.all()
    31      serializer_class = UserSerializer

This seems to be similar to:

Flask: google cloud debugger snapshot reports "No code found at line...", python on managed cloud run

FastAPI: Google Cloud Debugger snapshot reports error “No code found at line …”

As it seems that there are no answers and no issue has been opened yet, I opened one here:

Answers: 0