While trouble shooting something else, I used the Driver Manager in kubuntu System Settings (which uses Additional Drivers) to uninstall the nvidia driver (nvidia-driver-390). After finishing the trouble shooting, I attempted to reinstall the nvidia driver via Additional Drivers, and I'm getting this error as well.
After seeing message #1, I also attempted to launched the Discover package manager, and Discover is reporting the error as well: Cannot refresh cache whilst offline. I've recently run sudo apt update && sudo apt full-upgrade, so the system appears to be up to date. Distributor ID: Ubuntu Description: Ubuntu Impish Indri (development branch) Release: 21.10 Codename: impish -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1946196 Title: Additional Drivers fails with pk-client-error-quark: Cannot download packages whilst offline (257) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/software-properties/+bug/1946196/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs