super(type, obj): obj must be an instance or subtype of type

Question

I work on a small Django app and get an error tells me, super(type, obj): obj must be an instance or subtype of type. I get it from the view

Answer 1

Another interesting way is if a merge of branches has duplicated the class, so that in the file you have two definitions for the same name, e.g.

class A(Foo):
    def __init__(self):
        super(A, self).__init__()
        #...

class A(Foo):
    def __init__(self):
        super(A, self).__init__()
        #...

If you try to create an instance from a static reference to the first definition of A, once it tries to call super, inside the __init__ method, A will refer to the second definition of A, since it has been overwritten. The solution - ofcourse - is to remove the duplicate definition of the class, so it doesn't get overwritten.

This may seem like something that would never happen, but it just happened to me, when I wasn't paying close enough attention to the merge of two branches. My tests failed with the error message described in the question, so I thought I'd leave my findings here, even though it doesn't exactly answer the specific question.