Yes, you may need to mail out your return if you can't resolve this error.
First of all, there are two PINs on a tax return. The Self-Select PIN is a random five-digit number that you enter as your electronic signature when e-filing your return. You can't get a reject for that not matching.
The IP PIN is a six-digit number that the IRS assigns to victims of tax-related identity theft and people who request it for security reasons.
A new IP PIN is assigned each year. If you don't have your IP PIN letter for the 2023 tax return, you retrieve it from the IRS. Follow this link for more.
Once you get your IP PIN, here's where to enter it: