Have only tried this on Python 2.7 To reproduce: ~~~~~ from Tkinter import * import ttk root = Tk() tree = ttk.Treeview(root) id = tree.insert('' , 'end', text='foo', tag='bar') print tree.tag_has('bar', item=id) # ^ this works.. print tree.tag_has('baz', item=id) # ^ .. and this.. print tree.tag_has('bar') # ^ .. this doesn't. ~~~~~ ... self.tk.call(self._w, "tag", "has", tagname, item)) TypeError: must be string, not tuple Possibly introduced by Issue20072. Removing the self.tk.getboolean() wrapper in tag_has() appears to fix things.