Comment 21 for bug 1158686

Mauro, I was assuming that printer broadcasting via Avahi does not work for you. Your cupsd.conf makes the impression to me that your CUPS is not sharing your printers and that you perhaps need to adjust your configuration.

If your printers are actually broadcasted and your only problem is the ugliness of a failed second attempt to restart CUPS reported in the logs the problem is much less severe (your printing functionality is fully available) and an Upstart expert has to look into this issue.

What is your situation? Are your printers still no broadcasted, even after following the instructions of comment #19?