If you’re blocked by this error, this probably means you are not uploading the file sent by the organizer of the event, but in fact an edited version. This could be because you are uploading a screenshot, a scan or a split version of the file.
Please always make sure to download all tickets from the mail you got from the organizer. Only this full, unedited file will be accepted. You can always select which tickets you want to sell, and which ones you want to keep.