When I enter my street address, I get an error message telling me I "need to provide a street address, not a PO Box." But I AM providing a street address. Help!

I would suggest trying to close out of TurboTax and delete cookies and clear your cache Then sign back into your TurboTax account.
If that does not fix the issue, you may also contact customer care here.
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Unfortunately, there are zero ways around this. I live in a historical village and no one has a physical mail box. We all have PO Boxes. I had to back track through my taxes and change my way to pay to credit card instead of having it deducted from my return. Also super annoying is the only way to use a credit card is if you use Apple Pay. PLEASE FIX THIS GLITCH FOR NEXT YEAR!!!!!!! 

Go to the mailing address in My Info and put in the street address>Go back to filing and proceed a couple of screens>Go back to My Info and reenter the mailing address>Click Confirm>Select Filing again and verify the correct street address and proceed

I wasn't logged in. Once I logged in I was able to put in my PO Box and proceed.