A copy of a certification may only be uploaded if the expiration date has been changed or a new state certification entered.
If you are correcting an existing certification number, the upload feature is not needed.
It is not necessary to upload a copy since the National Registry forwards the information to FHA. If the information in those fields has not changed, the ability to upload is not needed because you are not changing any details of the certification.
For more information on Appraiser Roster Update Instructions go to https://www.hud.gov/program_offices/housing/sfh/appr/updates
For information on the ASC National Registry visit http://www.asc.gov