Error: Unsupported format ‘application/postscript’!

Well, it turns out the problem was I needed to update my ghostscript version to one that included the “pstoraster” filter (specifically, GNU ghostscript 8.60, though I assume GPL ghostscript 8.60/8.61 would be fine also. Let’s not get started on the ridiculous number of ghostscript variants; I’ll save that for another day). I could have been saved quite some time if this had been made more clear by the error message. How about something like:

Unsupported format ‘application/postscript’: Could not find “pstoraster” filter specified in /etc/cups/mime.convs file

That would be much more helpful! Yes, I understand it might not be meaningful for a casual PC user but then the original message is not helpful in that case anyway. Oh, and it gets rid of that annoying exclamation mark.

Still haven’t got the printer working though; now it just starts a whole bunch of processes (foomatic-rip, gs) which all just seem to hang.

Update: Ok ,several hours later I have got it working. It was permissions; I had to modify udev rules so that the usb device nodes were created with the right group and permissions. Incidentally, hplip (HP’s software) includes a udev rules file but it’s outdated (uses SYSFS instead of ATTR) and insecure (sets mode 0666 instead of 0660). I don’t know why the driver doesn’t try and open the device before running ghostscript and all that stuff.

Oh, and CUPS has a weird problem when you have only a single remote printer, and no local printers. For some reason, when I try and modify a class, the remote printer doesn’t come up in the list. I could add the remote printer to the class via the command line, however.