After further investigation I do agree that this is NOT an Synaptic issue.
However, your view about the cause is wrong I fear.
I do run Gnome 3.26 already.
I have a machine that is set up identically and synaptic works fine there.
I currently investigate why I cannot su root and call xhost even though access rights are set correctly.
Thanks for the hint though.
After further investigation I do agree that this is NOT an Synaptic issue.
However, your view about the cause is wrong I fear.
I do run Gnome 3.26 already.
I have a machine that is set up identically and synaptic works fine there.
I currently investigate why I cannot su root and call xhost even though access rights are set correctly.
Thanks for the hint though.