I’m glad I keep good backups. When backing up your Kubuntu box, do not just drag and drop one home folder from a hard disk to another hard disk.
Your ssh keys will not be copied over, even though you may have opened the Dolphin file manager over with the command
To ensure you have admin privileges over the copy procedure.
Instead, you should use a full copy command like this to ensure that you get everything, including files with 0400 permissions and all hidden files and folders (anything with a dot in front of it like this: ‘.ssh’).
sudo cp -R /home /your/backup/location/home
I’d normally cite some links to help you see more about this problem, but I discovered this one the hard way myself.