I had a huge set of Slackware changes come down a few days ago. I didn't notice any differences at first, but this morning I got bit.
I tried to print and nothing happened. I looked at the CUPS management page http:;//localhost:631, and two print jobs were banked up and just not printing. I remembered all the changes that had come down the pipe and thought I better reboot. Sometimes you can get away with not booting and sometimes you can't. I rebooted. Went back to the CUPS management page, and this time I could see the issue. I have a HP Laserjet 1300. CUPS was telling me that the PPD I had for this printer was HPLJ1300 + Gutenprint 5.2.6 and this was not good enough, it wanted 5.2.8. I tried to modify the printer, but this was "Forbidden".
Hmm. Maybe I had overwritten the cupsd.conf file when the update came down. Normally I prompt and check every config file that comes down with a Slackware change. Maybe I had made a mistake. I looked through things and it sure did not look familiar. In the end, I added my regular user to the right entry in /etc/group and continued. Now I could modify the printer setup. I chose HPLJ1300 + Gutenprint again, and went to print what I had originally wanted to print. It omitted page two and printed page 1 sideways and spread over two pages.
Last time there was a big CUPS change, I had problems too. It was printing PDFs reversed - huge amounts of black on every page. I solved that by switching to the HPLJ1300 + Gutenprint PPD. Nothing stays the same. I modified the printer again and looked at my PPD options. This time, the option "HP1300 Series Postscript" was recommended. Strange. I didn't think the 1300s had Postscript embedded. Oh well, it's recommended, so I selected it, printed my PDF again and it worked perfectly. That problem is solved.
I now have a number of things that have stopped functioning and they all relate to Python modules that were installed, but have now disappeared.
I had installed CDDB and DiscID and a DNS module. All things that depend on them will no longer work. The modules are not seen by Python. I can see in the ChangeLog.txt that Python upgraded to version 2.7.3. And I see the problem. I have two directories now - /usr/lib/python2.6 and /usr/lib/python2.7. Underneath both is a directory site-packages. Modules that were installed are still in /usr/lib/python2.6/site-packages, but are not in /usr/lib/python2.7/site-pacakges. I had this very same problem with Perl recently. I need to erase Python completely, then reinstall python-2.7. Then install my modules again.