Sorry, my fault, as Ante said:
"Local authentication certificate not found" in /var/log/cups/error_log aren't important. What's relevant in this log is "Print file was not accepted (Bad Request)".
So sorry for the confusion. Also, Ante is working on this. Please, patience.
Final Hint: if you write "see bug 44931" instead of "see #44931", the web interface generates a nice link to the bug report.
@WalterNicholls,
Sorry, my fault, as Ante said: cups/error_ log aren't important. What's relevant in this log is "Print file was not accepted (Bad Request)".
"Local authentication certificate not found" in /var/log/
So sorry for the confusion. Also, Ante is working on this. Please, patience.
Final Hint: if you write "see bug 44931" instead of "see #44931", the web interface generates a nice link to the bug report.