This came up as the top result in a Google search for this issue, so I am putting what helped me here. If you accidentally input something in the "Reference Number" box, try clearing that box. (My iPhone autocomplete accidentally put my address in that box, which caused the "unexpected error" message.)
This came up as the top result in a Google search for this issue, so I am putting what helped me here. If you accidentally input something in the "Reference Number" box, try clearing that box. (My iPhone autocomplete accidentally put my address in that box, which caused the "unexpected error" message.)