This same situation occurs on a lot of states. Try the following:
TurboTax tells you (correctly) that you need to have your SS number for your state return. It then offers a box and a worksheet to enter the SSN. Then, when you enter the SSN, it tells you "You can't do that here."
Obviously, this doesn't make any sense.
What you need to do is:
- erase this entry in the state return (because you won't be able to finish the state review so long as this entry is here).
- jump to your personal info on your federal return.
- add the missing information, like your SSN.
- then return to the state return and see if the state return will clear the review.
If that doesn't clear the state return, then you may have to delete the state return and re-enter it, so that the personal information on the federal return will be carried to the state anew.