Mac Cups Print file was not accepted (client-error-document-format-not-supported)!

“Print file was not accepted (client-error-document-format-not-supported)!”

Is the error line appearing in /var/log/cups/error_log on the Mac

The reason was this line:

in file /etc/cups/mime.convs on the server being commented out.

To enable raw printing of octet streams (what the mac sends with foomatic etc.) - the line needs to be uncommented. Otherwise the job will be rejected. You can only see this in the cups error_log file on the server with the cups LogLevel set to debug:

print_job: request file type is application/octet-stream.
Print-Job client-error-document-format-not-supported: Unsupported format ‘application/octet-stream’!

Remember Luke.