sudo apt-get autoremove gnome-keyring
Then I wasn't able to get a terminal for the debian-8 TemplateVM and all appVM's in relation to this TemplateVM.
So, I used this tutorial to reinstall a new debian-8 TemplateVM :
https://www.qubes-os.org/doc/reinstall-template/
The old-debian-8 template is deleted.
The new-debian-8 template is created and updated.
Now here's the problem ... when I try to change from dummy template to the new-debian-8 template I get this message :
[Dom0] Houston, we have a problem ...
OSError: [Errno 2] No such file or directory:
'/var/lib/qubes/vm-templates/dummy/apps.templates'
This is most likely a bug in the Qubes Manager
I want to access my files which are still in the appVM's created with the old-debian-8 template.
Thanks for your help
mkdir /var/lib/qubes/vm-templates/dummy/apps.templates
Then I was able to get a menu in Qubes VM Manager to switch from "dummy" to "debian-8" template.
All is working fine now.