I've noticed that when I make large prints on my Epson 9900 using Mac Snow Leopard and Lightroom, I sometimes get a message from CUPS (the Common Unix Printing System used by MacOS) that it can't open the spool file. This messages have the form: "can't open `/private/var/spool/cups/tmp/000ef50451e47'." I believe that this is a CUPS issue, and not specifically related to Lightroom.
When I look at the CUPS log (which you can do by pointing a browser to localhost:631), it appears that this happens when the spool file size exceeds about 2Gb. If I reduce the print resolution, or switch from 16-bit output to 8-bit output, the print jobs complete normally.
This suggests to me that CUPS may still be using 32-bit code, and that it chokes when the spool file is bigger than about 2^31 bytes long. Mr. Google surprised me by not providing a ready answer to this question - does anyone know if this is a CUPS limitation? Any workarounds, other than reducing the print file size?
Thanks!