Meaning of "AttributeError: NoneType object has no attribute tk"?

What does the following error message mean?

AttributeErro开发者_如何学Cr: 'NoneType' object has no attribute 'tk'

---

I have had this problem but found the solution. This problem arises when you declare the variable before you make an instance of Tk().

For example, this will bring the error

count = IntVar()
....
....
app = Tk()

Solution!! Make the declarations after creating a tkinter application window

app = Tk()
....
count = IntVar()

---

It means that in your code some where you are calling

x.tk

and x is None (NoneType).

x should have been an object that is assumed to have an attribute tk.

To solve this problem, you can check out where you are obtaining x and see why it is not returning an appropriate object.

---

It means that variable to the left of .tk is None.