user interface Button not working

[Frankduc]

Works ok for me. The code you provided is not the code that generated the error (line numbers don't match up). Verify that you are running this code

Why are you doing this?

mot = str(EntreeMot.get())
...
txtMot.configure(text = str(inversion))  # Should not be inside the loop

What is the type of EntreeMot.get()? Do you need to use the str() function? Same question for inversion?

def inverser():
    txtMot.configure(text = EntreeMot.get()[::-1])

I removed that part i dont need it: txtMot.configure(text = str(inversion))

the type is a string
its a palindrome code: You put "alla" and it tells you if it is or not a palindrome.