This worked for me as suggested above:
Changing the id in line 409 of /usr/share/update-manager/glade/DistUpgrade.ui to something like "vbox0" fixes the problem.
This worked for me as suggested above:
Changing the id in line 409 of /usr/share/ update- manager/ glade/DistUpgra de.ui to something like "vbox0" fixes the problem.