Dear Maintainer, I migrate a machine from wheezy to jessie and synaptic become unusable as it throw an error popup with the message : E: The value 'wheezy-backports' is invalid for APT::Default-Release as such a release is not available in the sources ... please report. When I close the dialog box synaptic ends. I have found the root of that problem in /root/.synaptic/synaptic.conf where there is the line : DefaultDistro "wheezy-backports"; I destroy that line and all is now OK. Regards JP P