No. First, I know the difference between a state letter code and a two digit numeric code. Second, it was not an error message. It was part of the questions when completing the process. When I entered the one digit, the program came back with a request for a 2 digit code from 'control number box d' on the W2. It stated if I didn't have a 2 digit number in that box, I could not efile and said to print and mail, which I did.
