[CentOS] can't create printers after upgrading cups

Wed Apr 26 13:51:19 UTC 2017
Vanhorn, Mike <michael.vanhorn at wright.edu>

After upgrading cups on my CentOS 6 systems from version 1.4.2-72.el6 to 1.4.2-77.el6, I am no longer able to create working printers, either with lpadmin from the command line or with system-config-printer. 

When I try to run lpadmin, I get this simple error:

[root at vlsi66 ~]# lpadmin -p newprinter  -v lpd://printserver/serverqueue-E -P /path/to/ppd/thing.ppd
lpadmin: Unknown
[root at vlsi66 ~]#

Sometimes, the printer does get created (i.e. it shows up in the output of ‘lpstat –a’ and printers.conf gets updated), but sometimes it doesn’t. If the printer does get created, then there is no new ppd in /etc/cups/ppd.

If I try to create the printer using system-config-printer, I get an error of 

 CUPS server error (adding printer newprinter) 
 There was an error during the CUPS 
 operation: ‘server-error-service-unavailable’.

I’ve looked at file and directory permissions, and checked that cupsd is, in fact, running. There is nothing obvious in the logs, except for this, which happens at exactly the time the printer should get created:

localhost - - [26/Apr/2017:09:34:01 -0400] "POST /admin/ HTTP/1.1" 401 0 - -

This also occurs if I access localhost:631 from a web browser; and everything works fine up to the point of “Add Printer”, and then the web page shows and Error: box with “Unknown” (from the lpadmin command), and the 401 error shows up in the log. I can’t figure out why it would be a 401 (unauthorized), since everything else worked.

Has anyone else run into this problem, where you can’t create a new printer?


Mike VanHorn
Senior Computer Systems Administrator
College of Engineering and Computer Science
Wright State University
265 Russ Engineering Center
michael.vanhorn at wright.edu