Synaptic broke

[Michael Milliman <michael.e.milliman@gmail.com>]

I just ran across a problem with synaptic.  When I start this program, I get a dialog box saying:

The value 'jessie-backports' is invalid for APT::Default-Release as such a release is not available in the sources

Synaptic then exits with no opportunity to make any changes.
I have tried to find where this setting is to fix it, but have had no luck.  I have purged and re-installed synaptic with no luck.
I am running a fully updated jessie (8.7) system.
Anyone have any ideas how to repair this??

-- 
73's de Mike, WB5VQX