If you have a site with download images to local unset and it links to a discourse forum and includes a onebox that includes an image with /uploads/default/original in it you can’t restore the database.
https://github.com/discourse/discourse/blob/main/lib/file_store/to_s3_migration.rb#L78
I solved this by putting a space before the oneboxed Discourse link so that it did an inline link rather than a onebox.
Don’t know why they have download images turned off. . .