I think I found the cause of the problem! It's a permissions issue. I enabled "LogLevel debug2" in /etc/cups/cupsd.conf, then opened error log with "tail -f /var/log/cups/error_log". When I access, for example, the error log in the browser (http://localhost:631/admin/log/error_log), these interesting messages are printed:
I [22/Aug/2014:14:11:19 +0100] [Client 15] Files/directories such as "/var/log/cups/error_log" must be world-readable. d [22/Aug/2014:14:11:19 +0100] [Client 15] cupsdSendError code=404, auth_type=0 D [22/Aug/2014:14:11:19 +0100] [Client 15] Closing because Keep-Alive disabled D [22/Aug/2014:14:11:19 +0100] [Client 15] Closing connection. And, indeed, the /var/log/cups/error_log file is not world-readable. In fact, the permissions are: -rw-r----- root adm If I run: sudo chmod o+r /var/log/cups/error_log then try to access the logs again, it works. When trying to access the server settings through system-config-printer, the same messages are printed, but for the /etc/cups/cupsd.conf file. Its permissions are: -rw-r----- root lp Running the chmod for that file fixes the issue, and lets you access the server settings... until the OK button in that dialog is pressed. Then the permissions are reverted and the problem appears again! That's why the problem didn't occur in the first time. Therefore, the problem is in cups, not in system-config-printer! Changing the permissions (and not reverting them) would fix the problem, but I don't know what are the security implications. -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to cups in Ubuntu. https://bugs.launchpad.net/bugs/1349387 Title: server settings are inaccessible Status in “cups” package in Ubuntu: Confirmed Status in “system-config-printer” package in Ubuntu: Confirmed Bug description: When trying to access server settings via gnome gui in trusty I get a cups server error: "There was an HTTP error: Not found." Adding/removing printers with the gui works fine. The server settings are accessible via a web browser and the web interface. system-config-printer --debug (when calling the settings menu entry): Connected as user kiran Authentication pass: 1 Authentication: password callback set PolicyKit call to FileGet did not work: dbus.String(u'Not Found') Authentication pass: 2 Forbidden: False Authentication: Try as root Connected as user root Authentication pass: 3 Forbidden: False Authentication: giving up cups access.log: localhost - - [28/Jul/2014:13:40:42 +0200] "GET /admin/conf/cupsd.conf HTTP/1.1" 401 0 - - localhost - root [28/Jul/2014:13:40:42 +0200] "GET /admin/conf/cupsd.conf HTTP/1.1" 404 0 - - localhost - root [28/Jul/2014:13:40:42 +0200] "GET /admin/conf/cupsd.conf HTTP/1.1" 404 0 - - localhost - - [28/Jul/2014:13:40:42 +0200] "GET /admin/conf/cupsd.conf HTTP/1.1" 401 0 - - localhost - root [28/Jul/2014:13:40:42 +0200] "GET /admin/conf/cupsd.conf HTTP/1.1" 404 0 - - localhost - root [28/Jul/2014:13:40:42 +0200] "GET /admin/conf/cupsd.conf HTTP/1.1" 404 0 - - localhost - root [28/Jul/2014:13:40:42 +0200] "GET /admin/conf/cupsd.conf HTTP/1.1" 404 0 - - localhost - root [28/Jul/2014:13:40:42 +0200] "GET /admin/conf/cupsd.conf HTTP/1.1" 404 0 - - cups error.log: D [28/Jul/2014:13:41:22 +0200] [Client 15] Accepted from localhost (Domain) D [28/Jul/2014:13:41:22 +0200] [Client 15] Waiting for request. D [28/Jul/2014:13:41:22 +0200] cupsd is not idle any more, canceling shutdown. D [28/Jul/2014:13:41:22 +0200] [Client 16] Accepted from localhost (Domain) D [28/Jul/2014:13:41:22 +0200] [Client 16] Waiting for request. D [28/Jul/2014:13:41:22 +0200] cupsd is not idle any more, canceling shutdown. D [28/Jul/2014:13:41:23 +0200] [Client 16] GET /admin/conf/cupsd.conf HTTP/1.1 D [28/Jul/2014:13:41:23 +0200] cupsdSetBusyState: newbusy="Active clients", busy="Not busy" D [28/Jul/2014:13:41:23 +0200] [Client 16] No authentication data provided. D [28/Jul/2014:13:41:23 +0200] cupsdIsAuthorized: username="" D [28/Jul/2014:13:41:23 +0200] [Client 16] WWW-Authenticate: Basic realm="CUPS", trc="y" D [28/Jul/2014:13:41:23 +0200] [Client 16] Closing connection. D [28/Jul/2014:13:41:23 +0200] cupsdSetBusyState: newbusy="Not busy", busy="Active clients" D [28/Jul/2014:13:41:23 +0200] cupsd is not idle any more, canceling shutdown. D [28/Jul/2014:13:41:23 +0200] [Client 16] Accepted from localhost (Domain) D [28/Jul/2014:13:41:23 +0200] [Client 16] Waiting for request. D [28/Jul/2014:13:41:23 +0200] cupsd is not idle any more, canceling shutdown. D [28/Jul/2014:13:41:23 +0200] [Client 16] HTTP_STATE_WAITING Closing on EOF D [28/Jul/2014:13:41:23 +0200] [Client 16] Closing connection. D [28/Jul/2014:13:41:23 +0200] cupsdSetBusyState: newbusy="Not busy", busy="Not busy" D [28/Jul/2014:13:41:23 +0200] cupsd is not idle any more, canceling shutdown. D [28/Jul/2014:13:41:23 +0200] [Client 16] Accepted from localhost (Domain) D [28/Jul/2014:13:41:23 +0200] [Client 16] Waiting for request. D [28/Jul/2014:13:41:23 +0200] cupsd is not idle any more, canceling shutdown. D [28/Jul/2014:13:41:23 +0200] [Client 16] HTTP_STATE_WAITING Closing on EOF D [28/Jul/2014:13:41:23 +0200] [Client 16] Closing connection. D [28/Jul/2014:13:41:23 +0200] cupsdSetBusyState: newbusy="Not busy", busy="Not busy" D [28/Jul/2014:13:41:23 +0200] cupsd is not idle any more, canceling shutdown. D [28/Jul/2014:13:41:23 +0200] [Client 16] Accepted from localhost (Domain) D [28/Jul/2014:13:41:23 +0200] [Client 16] Waiting for request. D [28/Jul/2014:13:41:23 +0200] cupsd is not idle any more, canceling shutdown. D [28/Jul/2014:13:41:23 +0200] [Client 16] GET /admin/conf/cupsd.conf HTTP/1.1 D [28/Jul/2014:13:41:23 +0200] cupsdSetBusyState: newbusy="Active clients", busy="Not busy" D [28/Jul/2014:13:41:23 +0200] [Client 16] Authorized as root using PeerCred D [28/Jul/2014:13:41:23 +0200] cupsdIsAuthorized: username="root" I [28/Jul/2014:13:41:23 +0200] [Client 16] Files/directories such as "/etc/cups/cupsd.conf" must be world-readable. D [28/Jul/2014:13:41:23 +0200] [Client 16] Closing because Keep-Alive disabled D [28/Jul/2014:13:41:23 +0200] [Client 16] Closing connection. D [28/Jul/2014:13:41:23 +0200] cupsdSetBusyState: newbusy="Not busy", busy="Active clients" D [28/Jul/2014:13:41:23 +0200] cupsd is not idle any more, canceling shutdown. D [28/Jul/2014:13:41:23 +0200] [Client 16] Accepted from localhost (Domain) D [28/Jul/2014:13:41:23 +0200] [Client 16] Waiting for request. D [28/Jul/2014:13:41:23 +0200] cupsd is not idle any more, canceling shutdown. D [28/Jul/2014:13:41:23 +0200] [Client 16] HTTP_STATE_WAITING Closing on EOF D [28/Jul/2014:13:41:23 +0200] [Client 16] Closing connection. D [28/Jul/2014:13:41:23 +0200] cupsdSetBusyState: newbusy="Not busy", busy="Not busy" D [28/Jul/2014:13:41:23 +0200] cupsd is not idle any more, canceling shutdown. D [28/Jul/2014:13:41:23 +0200] [Client 16] Accepted from localhost (Domain) D [28/Jul/2014:13:41:23 +0200] [Client 16] Waiting for request. D [28/Jul/2014:13:41:23 +0200] cupsd is not idle any more, canceling shutdown. D [28/Jul/2014:13:41:23 +0200] [Client 16] HTTP_STATE_WAITING Closing on EOF D [28/Jul/2014:13:41:23 +0200] [Client 16] Closing connection. D [28/Jul/2014:13:41:23 +0200] cupsdSetBusyState: newbusy="Not busy", busy="Not busy" D [28/Jul/2014:13:41:23 +0200] cupsd is not idle any more, canceling shutdown. D [28/Jul/2014:13:41:23 +0200] [Client 16] Accepted from localhost (Domain) D [28/Jul/2014:13:41:23 +0200] [Client 16] Waiting for request. D [28/Jul/2014:13:41:23 +0200] cupsd is not idle any more, canceling shutdown. D [28/Jul/2014:13:41:23 +0200] [Client 16] GET /admin/conf/cupsd.conf HTTP/1.1 D [28/Jul/2014:13:41:23 +0200] cupsdSetBusyState: newbusy="Active clients", busy="Not busy" D [28/Jul/2014:13:41:23 +0200] [Client 16] Authorized as root using PeerCred D [28/Jul/2014:13:41:23 +0200] cupsdIsAuthorized: username="root" I [28/Jul/2014:13:41:23 +0200] [Client 16] Files/directories such as "/etc/cups/cupsd.conf" must be world-readable. D [28/Jul/2014:13:41:23 +0200] [Client 16] Closing because Keep-Alive disabled D [28/Jul/2014:13:41:23 +0200] [Client 16] Closing connection. D [28/Jul/2014:13:41:23 +0200] cupsdSetBusyState: newbusy="Not busy", busy="Active clients" D [28/Jul/2014:13:41:23 +0200] cupsd is not idle any more, canceling shutdown. D [28/Jul/2014:13:41:23 +0200] [Client 15] GET /admin/conf/cupsd.conf HTTP/1.1 D [28/Jul/2014:13:41:23 +0200] cupsdSetBusyState: newbusy="Active clients", busy="Not busy" D [28/Jul/2014:13:41:23 +0200] [Client 15] No authentication data provided. D [28/Jul/2014:13:41:23 +0200] cupsdIsAuthorized: username="" D [28/Jul/2014:13:41:23 +0200] [Client 15] WWW-Authenticate: Basic realm="CUPS", trc="y" D [28/Jul/2014:13:41:23 +0200] [Client 15] Closing connection. D [28/Jul/2014:13:41:23 +0200] cupsdSetBusyState: newbusy="Not busy", busy="Active clients" D [28/Jul/2014:13:41:23 +0200] cupsd is not idle any more, canceling shutdown. D [28/Jul/2014:13:41:23 +0200] [Client 15] Accepted from localhost (Domain) D [28/Jul/2014:13:41:23 +0200] [Client 15] Waiting for request. D [28/Jul/2014:13:41:23 +0200] cupsd is not idle any more, canceling shutdown. D [28/Jul/2014:13:41:23 +0200] [Client 16] Accepted from localhost (Domain) D [28/Jul/2014:13:41:23 +0200] [Client 16] Waiting for request. D [28/Jul/2014:13:41:23 +0200] [Client 15] HTTP_STATE_WAITING Closing on EOF D [28/Jul/2014:13:41:23 +0200] [Client 15] Closing connection. D [28/Jul/2014:13:41:23 +0200] cupsdSetBusyState: newbusy="Not busy", busy="Not busy" D [28/Jul/2014:13:41:23 +0200] cupsd is not idle any more, canceling shutdown. D [28/Jul/2014:13:41:23 +0200] [Client 15] Accepted from localhost (Domain) D [28/Jul/2014:13:41:23 +0200] [Client 15] Waiting for request. D [28/Jul/2014:13:41:23 +0200] [Client 16] HTTP_STATE_WAITING Closing on EOF D [28/Jul/2014:13:41:23 +0200] [Client 16] Closing connection. D [28/Jul/2014:13:41:23 +0200] cupsdSetBusyState: newbusy="Not busy", busy="Not busy" D [28/Jul/2014:13:41:23 +0200] cupsd is not idle any more, canceling shutdown. D [28/Jul/2014:13:41:23 +0200] [Client 15] GET /admin/conf/cupsd.conf HTTP/1.1 D [28/Jul/2014:13:41:23 +0200] cupsdSetBusyState: newbusy="Active clients", busy="Not busy" D [28/Jul/2014:13:41:23 +0200] [Client 15] Authorized as root using Local D [28/Jul/2014:13:41:23 +0200] cupsdIsAuthorized: username="root" I [28/Jul/2014:13:41:23 +0200] [Client 15] Files/directories such as "/etc/cups/cupsd.conf" must be world-readable. D [28/Jul/2014:13:41:23 +0200] [Client 15] Closing because Keep-Alive disabled D [28/Jul/2014:13:41:23 +0200] [Client 15] Closing connection. D [28/Jul/2014:13:41:23 +0200] cupsdSetBusyState: newbusy="Not busy", busy="Active clients" D [28/Jul/2014:13:41:23 +0200] cupsd is not idle any more, canceling shutdown. D [28/Jul/2014:13:41:23 +0200] [Client 15] Accepted from localhost (Domain) D [28/Jul/2014:13:41:23 +0200] [Client 15] Waiting for request. D [28/Jul/2014:13:41:23 +0200] cupsd is not idle any more, canceling shutdown. D [28/Jul/2014:13:41:23 +0200] [Client 16] Accepted from localhost (Domain) D [28/Jul/2014:13:41:23 +0200] [Client 16] Waiting for request. D [28/Jul/2014:13:41:23 +0200] [Client 15] HTTP_STATE_WAITING Closing on EOF D [28/Jul/2014:13:41:23 +0200] [Client 15] Closing connection. D [28/Jul/2014:13:41:23 +0200] cupsdSetBusyState: newbusy="Not busy", busy="Not busy" D [28/Jul/2014:13:41:23 +0200] cupsd is not idle any more, canceling shutdown. D [28/Jul/2014:13:41:23 +0200] [Client 16] GET /admin/conf/cupsd.conf HTTP/1.1 D [28/Jul/2014:13:41:23 +0200] cupsdSetBusyState: newbusy="Active clients", busy="Not busy" D [28/Jul/2014:13:41:23 +0200] [Client 16] Authorized as root using PeerCred D [28/Jul/2014:13:41:23 +0200] cupsdIsAuthorized: username="root" I [28/Jul/2014:13:41:23 +0200] [Client 16] Files/directories such as "/etc/cups/cupsd.conf" must be world-readable. D [28/Jul/2014:13:41:23 +0200] [Client 16] Closing because Keep-Alive disabled D [28/Jul/2014:13:41:23 +0200] [Client 16] Closing connection. D [28/Jul/2014:13:41:23 +0200] cupsdSetBusyState: newbusy="Not busy", busy="Active clients" D [28/Jul/2014:13:41:23 +0200] cupsd is not idle any more, canceling shutdown. D [28/Jul/2014:13:41:23 +0200] [Client 15] Accepted from localhost (Domain) D [28/Jul/2014:13:41:23 +0200] [Client 15] Waiting for request. D [28/Jul/2014:13:41:23 +0200] cupsd is not idle any more, canceling shutdown. D [28/Jul/2014:13:41:23 +0200] [Client 16] Accepted from localhost (Domain) D [28/Jul/2014:13:41:23 +0200] [Client 16] Waiting for request. D [28/Jul/2014:13:41:23 +0200] [Client 15] HTTP_STATE_WAITING Closing on EOF D [28/Jul/2014:13:41:23 +0200] [Client 15] Closing connection. D [28/Jul/2014:13:41:23 +0200] cupsdSetBusyState: newbusy="Not busy", busy="Not busy" D [28/Jul/2014:13:41:23 +0200] cupsd is not idle any more, canceling shutdown. D [28/Jul/2014:13:41:23 +0200] [Client 15] Accepted from localhost (Domain) D [28/Jul/2014:13:41:23 +0200] [Client 15] Waiting for request. D [28/Jul/2014:13:41:23 +0200] [Client 16] HTTP_STATE_WAITING Closing on EOF D [28/Jul/2014:13:41:23 +0200] [Client 16] Closing connection. D [28/Jul/2014:13:41:23 +0200] cupsdSetBusyState: newbusy="Not busy", busy="Not busy" D [28/Jul/2014:13:41:23 +0200] cupsd is not idle any more, canceling shutdown. D [28/Jul/2014:13:41:23 +0200] [Client 15] GET /admin/conf/cupsd.conf HTTP/1.1 D [28/Jul/2014:13:41:23 +0200] cupsdSetBusyState: newbusy="Active clients", busy="Not busy" D [28/Jul/2014:13:41:23 +0200] [Client 15] Authorized as root using PeerCred D [28/Jul/2014:13:41:23 +0200] cupsdIsAuthorized: username="root" I [28/Jul/2014:13:41:23 +0200] [Client 15] Files/directories such as "/etc/cups/cupsd.conf" must be world-readable. D [28/Jul/2014:13:41:23 +0200] [Client 15] Closing because Keep-Alive disabled D [28/Jul/2014:13:41:23 +0200] [Client 15] Closing connection. D [28/Jul/2014:13:41:23 +0200] cupsdSetBusyState: newbusy="Not busy", busy="Active clients" D [28/Jul/2014:13:41:23 +0200] cupsd is not idle any more, canceling shutdown. D [28/Jul/2014:13:41:23 +0200] [Client 15] Accepted from localhost (Domain) D [28/Jul/2014:13:41:23 +0200] [Client 15] Waiting for request. D [28/Jul/2014:13:41:23 +0200] cupsd is not idle any more, canceling shutdown. D [28/Jul/2014:13:41:23 +0200] [Client 16] Accepted from localhost (Domain) D [28/Jul/2014:13:41:23 +0200] [Client 16] Waiting for request. D [28/Jul/2014:13:41:23 +0200] [Client 15] HTTP_STATE_WAITING Closing on EOF D [28/Jul/2014:13:41:23 +0200] [Client 15] Closing connection. D [28/Jul/2014:13:41:23 +0200] cupsdSetBusyState: newbusy="Not busy", busy="Not busy" D [28/Jul/2014:13:41:23 +0200] cupsd is not idle any more, canceling shutdown. D [28/Jul/2014:13:41:23 +0200] [Client 16] GET /admin/conf/cupsd.conf HTTP/1.1 D [28/Jul/2014:13:41:23 +0200] cupsdSetBusyState: newbusy="Active clients", busy="Not busy" D [28/Jul/2014:13:41:23 +0200] [Client 16] Authorized as root using Local D [28/Jul/2014:13:41:23 +0200] cupsdIsAuthorized: username="root" I [28/Jul/2014:13:41:23 +0200] [Client 16] Files/directories such as "/etc/cups/cupsd.conf" must be world-readable. D [28/Jul/2014:13:41:23 +0200] [Client 16] Closing because Keep-Alive disabled D [28/Jul/2014:13:41:23 +0200] [Client 16] Closing connection. D [28/Jul/2014:13:41:23 +0200] cupsdSetBusyState: newbusy="Not busy", busy="Active clients" D [28/Jul/2014:13:41:23 +0200] cupsd is not idle any more, canceling shutdown. D [28/Jul/2014:13:41:24 +0200] cupsd is not idle any more, canceling shutdown. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/cups/+bug/1349387/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp