Looks like you are affected with bug 561046. Please reinstall 'command-not-found' and 'command-not-found-data' package and try launching 'rhythmbox-client' commands again.
Looks like you are affected with bug 561046. not-found- data'
Please reinstall 'command-not-found' and 'command-
package and try launching 'rhythmbox-client' commands again.