Box 20 about locality name is blank on my w2. Review keeps telling me box 20 needs something what do I do?

Not every box on the W2 is reported or needs to be reported.

If Box 19 is blank, leave Box 20 blank as well. If there is an amount in Box 19, it would indicate that local tax was withheld from your wages and paid to a local government, such as to a city tax.

If you have an amount in box 19, and Box 20 is blank, ask your employer who they paid with the proceeds reported in Box 19.