Additional information.
I just succeeded by first installing Synaptic, and then I have been able to execute the commands to install the Guest Additions.
Looks to me as if the installation if Synaptic did in effect register the repos.
Additional information.
I just succeeded by first installing Synaptic, and then I have been able to execute the commands to install the Guest Additions.
Looks to me as if the installation if Synaptic did in effect register the repos.