Thank you for your suggestions, which solved the issue. First I executed, as suggested, the command xattr -d com.apple.quarantine <path to .png file> which output "No such xattr: com.apple.quarantine" Then I rebuilt the archive and executed xattr -lr and searched the output for "com.apple.quarantine" The only file found was the .png file the attribute had been deleted from. Message was "com.apple.quarantine: 0082;5f0206c2;Preview;" One can conclude the xattr -d failed to remove the quarantine attribute even though the output said there was no such attribute. Next I execute the command xattr -cr No output Finally ran the command xattr -lr No file had the quaranting attribute. The quarantine attribute on the .png file had been removed. Uploaded the archive again; it was accepted. Conclusion: If the archive is rejected because it has a file with the quarantine attribute, run xattr -cr on the archive to remove it. Then upload the archive again.