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.