My asus running debian ceased to print to my printer sometime in the last 6 months. At the time, I was thinking I was moving to a new computer pretty soon and so I just left it. Today I took a few minutes and fixed it.

The symptom was that everytime I would go to print the hplip would somehow pop up a dialog saying that the plugin was missing. I would follow the steps install the plugin and try again and still no luck, it would just tell me that the plugn was missing and prompt me to install. Repeat ad naseum.

So finally I read the syslog to see what was going on, and what did I find...

Feb 22 16:47:21 helmcken hpcups[9257]: common/utils.c 69: unable to open /var/lib/hp/hplip.state: Permission denied
Feb 22 16:47:21 helmcken hpcups[9257]: common/utils.c 119: validate_plugin_version() Failed to get Plugin version from [/var/lib/hp/hplip.state]
Feb 22 16:47:21 helmcken hpcups[9257]: common/utils.c 157: Plugin version is not matching 

So, I checked the permissions on the /var/lib/hp/hplip.state and sure enough the permissions were set to 744 so that seemed okay. BUT the permissions on the /var/lib/hp folder were also 744 so a regular user couldn't access the file, why oh why wasn't the directory set to 755 so that the average user could read the hplip.state file? No idea. So change the permissions and I changed them on both the folder and the file for good measure.

~$ sudo chmod 755 /var/lib/hp
~$ sudo chmod 755 /var/lib/hp/hplip.state

And it worked! Hurray!

The gotcha, that got me, was that I was repeatedly installing the driver, and that process was resetting the permissions, so presently I imagine that I will have to reset the permissions next time I update the hplip-plugin.