Hi ivan
A quick look shows this problem occurs several times:-
D [20/Jan/2015:23:20:04 -0100] [Job

] Auto-typing file...
I [20/Jan/2015:23:20:04 -0100] [Job

] Request file type is application/vnd.cups-banner.
D [20/Jan/2015:23:20:04 -0100] Print-Job client-error-document-format-not-supported: Unsupported format "application/vnd.cups-banner".
E [20/Jan/2015:23:20:04 -0100] [Client 37] Returning IPP client-error-document-format-not-supported for Print-Job (ipp://localhost:631/printers/lp) from localhost
a little further down I see:-
D [20/Jan/2015:23:20:05 -0100] [CGI] cgiSetVariable: CUPS_VERSION="CUPS v2.0.0"
D [20/Jan/2015:23:20:05 -0100] [CGI] cgiSetArray: document_format[0]="application/vnd.cups-banner"
D [20/Jan/2015:23:20:05 -0100] [CGI] cgiSetVariable: TITLE="Print Test Page"
D [20/Jan/2015:23:20:05 -0100] [CGI] cgiSetVariable: SERVER_NAME="localhost"
D [20/Jan/2015:23:20:05 -0100] [CGI] cgiSetVariable: CUPS_VERSION="CUPS v2.0.0"
D [20/Jan/2015:23:20:05 -0100] [Client 36] CGI data ready to be sent.
D [20/Jan/2015:23:20:05 -0100] [CGI] cgiSetVariable: MESSAGE="Unable to print test page"
D [20/Jan/2015:23:20:05 -0100] [CGI] cgiSetVariable: ERROR="Unsupported format "application/vnd.cups-banner"."
I would expect cups to be able to print it's own test page but obiously something is wrong. May be there is a missing filter in your cups setup?
Does the printer use the cups hplip package?
Regards
Pete