HPLIP Troubleshooting - General/Other

# HP Linux Imaging and Printing (HPLIP)

About Features Screenshots FAQs Setup and Installation System Requirements Supported Devices Download HPLIP Installation Instructions Usage and Support Mailing Lists How-Tos Troubleshooting Release Notes Resources Technical Documentation Sourceforge Project Page Software License Other Support Information About HPLIP Contacts Home > Troubleshooting > General/Other | # General/Other Troubleshooting Issue 1: I am seeing messages like "Unable to find GUI for username..." and "No GUI available" in the system log. Solution: These are normal and should not cause any concerns. Issue 2: How do I check the syslog for HPLIP system errors? Solution: With superuser (su/sudo) privileges, use the following command to view the syslog. Look for any errors during the time of the failure.
    # tail -f /var/log/messages
Issue 3: How to debug HPLIP. Solution: Debugging HPLIP is a several step process. Use su/sudo as applicable for your configuration and step. The HPSSD process provides various services to HPLIP client applications. Maintains persistant device status. Putting hpssd in debug mode will assist in troubleshooting connection problems. This will restart HPLIP and CUPS:
    # /etc/init.d/hplip restart
    # /etc/init.d/cups restart
for Ubuntu
    $ /etc/init.d/cupsys restart
Go to the hplip working directory:
    cd /usr/share/hplip
Find the hpssd.py process number:
    # ps ax | grep hp
Find the line that looks like:
    4193 ?        S      0:00 python ./hpssd.py
Kill the hpssd.py process:
    # kill 4193
for Ubuntu
    $ sudo kill 4193
Start the hpssd.py process in debug mode:
    # python ./hpssd.py -g
You should see something like this:
    hpssd [DEBUG]: port=36181
    hpssd Listening on localhost:36181
    hpssd [DEBUG]: Starting async loop...
Then open a new terminal/console window: (Shift-Control-T if you are using Terminal) Run the hp-toolbox in debug mode:
    # hp-toolbox -g
Attempt to do the function you are having issues with, when the error occurs, note the information displayed for both the hp-toolbox and for hpssd. Issue 4: When I go to login to the CUPS web interface (http://localhost:631) it asks for my root password--and my root password doesn't give me access. Solution: First verify with your distribution the proper way in each to install a printer for your system. To enable the CUPS web interface follow these directions. Edit the cupsd.conf file.
    # gedit /etc/cups/cupsd.conf
Find this section:
    # Restrict access to the admin pages...
    <Location /admin>
    #Order allow,deny
    #Allow localhost
    </Location>
Change it to:
    # Restrict access to the admin pages...
    <Location /admin>
    Order allow,deny
    Allow localhost
    </Location>
Save/Exit, restart CUPS:
    # /etc/init.d/cups restart
for Ubuntu
    $ /etc/init.d/cupsys restart
Open your web browser, go to http://localhost:631. Complete the administrative tasks you need to complete. Last update: Thu Mar 16 17:21:05 2006; HPLIP Version: 1.6.9