Why does this if condition always evaluate to false? [GoLang]

I have the following if condition that evaluates the length of string foo – it should always be either 16 or 19 characters. It’ll look something like abcd-efgh-ijkl-mnop or abcdefghijklmnop.

func ValidateFoo(...) error {

    if len(foo) != 16 || len(foo) != 19 {
        return fmt.Errorf("foo should be 16 or 19 characters, %q %d",
            foo,
            len(foo),
        )
    }
...
}

This looks syntactically correct (to me) but when I run tests against this function, they fail with the "foo should be 16 or 19 characters" error.

Strangely, in the output of Errorf(), the len() is always 16 or 19 characters, which obviously makes no sense. eg:

got error: supplied key is not 16 or 19 characters, key "foo should be 16 or 19 characters" 19

Is my if statement wrong?

Edit:

My if statement is wrong. Should use logical AND not OR https://stackoverflow.com/a/72889607/8859720

>Solution :

The if statement is always true. For it to be false, len(foo) must be both 16 and 19. Use &&, not ||.