Comment 2 for bug 1935699

Hello! Sorry for the delay in responding and that Deja Dup is giving you trouble.

Can you try running the following command, then trying to restore again?

gsettings set org.gnome.DejaDup root-prompt false

This will disable that superuser password prompt you see in your screenshot and just try to restore even if we think we need superuser access (which sometimes we get wrong). There were enough issues with our attempt to use superuser access that we stopped doing it at all in versions 42.0 and up. But in your version, you can get that same result with the above command.