Apologies if these questions have been asked before. We're about to take our first trip outside the US in the covid era.

I'm returning to the US in a couple weeks, ATH-MUC on LH and then MUC-IAD on UA. (Outbound is all AA/BA.)

I assume I need to use United's Travel Ready Center to input passport information. My first problem is that it rejects my passport's expiration date as invalid. No matter what I put in there, it's always an error message...I can't get past the screen.

The reason I'm trying to do this now is because one of our passengers will be using a positive covid test and signed letter from a doctor in lieu of a negative test the day prior to the return flight. I'd like to upload this now, prior to leaving the USA, as I assume there's some sort of verification process. There was no set CDC form for the physician letter, so our doctor typed one up. If it is not valid, then we'll have to get a covid test abroad... Not the end of the world, but I'd like to know that now, not the day prior to our return.

Anyone know how to get past the passport expiry date problem and onto the screen where I can upload the forms?