Cannot use geometry manager pack inside

The reason of the code is simple, you CANNOT use pack and grid inside the same class or for the same frame. Thus, use only one.

You can't use pack and grid inside the same class or the same frame.use only one

Per the docs, don't mix pack and grid in the same master window:

Warning: Never mix grid and pack in the same master window. Tkinter will happily spend the rest of your lifetime trying to negotiate a solution that both managers are happy with. Instead of waiting, kill the application, and take another look at your code. A common mistake is to use the wrong parent for some of the widgets.

Thus, if you call grid on the textbox, do not call pack on the scrollbar.

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import Tkinter as tk
import ttk

class App(object):
    def __init__(self, master, **kwargs):
        self.master = master
        self.create_text()

    def create_text(self):
        self.textbox = tk.Text(self.master, height = 10, width = 79, wrap = 'word')
        vertscroll = ttk.Scrollbar(self.master)
        vertscroll.config(command=self.textbox.yview)
        self.textbox.config(yscrollcommand=vertscroll.set)
        self.textbox.grid(column=0, row=0)
        vertscroll.grid(column=1, row=0, sticky='NS')

root = tk.Tk()
app = App(root)
root.mainloop()