Ubuntu > Filter directory /usr/lib/cups/filter for printer "<yourprinter>" is not owned by root.

Problem

You receive the following error status message for a printer, once it is installed (e.g. in the "Print" window).

Filter directory /usr/lib/cups/filter for printer "" is not owned by root. 

You may also see "cups-insecure-filter". 

Solution

Execute the following commands, to change ownership back to root. 

1. sudo chown -hR root:root /usr/lib/cups/filter/* 
2. sudo chown -hR root:root /usr/lib/cups/backend/* 
3. service cups restart 

Your printer should now no longer display the message. (May require closing and reopening the "Print" window). 

See also:
https://bugs.launchpad.net/ubuntu/+source/cups/+bug/436544