Although an in-date passport is preferred, we understand that many applicants do not have one. You can upload an out-of-date passport, but only if it expired in the last 6 months, and only if it's a UK passport.
Alternatively, you could upload your birth certificate and the birth certificate of one of your parents (if they were born in the UK; if not, you will need their naturalisation certificate). Either way, the passport section must have a file uploaded in it – so if you don't have one, make sure your birth certificate is uploaded in that field instead, or you won't be able to move forward.
