I am flying to Japan via United, and their Travel Ready Center is rejecting my vaccine documentation even though I am fully vaccinated. What's wrong?
You may notice that your first and middle name is merged in the name field they've forced upon you. Bad programmers.
This will obviously not match a US COVID-19 Vaccine Record Card, and so your card will be rejected.
To solve this, in the United Airlines app, upload your vaccine documentation in your profile > TSA Precheck®️ and travel documents > COVID-19 Vaccine Documentation
This one does not merge your first and middle name together. Go back to the Travel Ready Center and upload your vaccine documentation again. This time, a pop-up will appear, allowing you to use the documentation you previously uploaded, without uploading a new file. Documentation verification should pass this time, allowing you to check-in using the app.
Failing this, you need to physically go to check-in or the gate with your documentation and they'll sort the mess out for you