Symptoms: After upgrading a dual-boot system from 19.10 to 20.04LTS, mouse and keyboard don't work. No input from either device is recognised, so switching to a tty is not possible. Pressing CTRL-ALT-DEL causes instant reboot without the normal shutdown dialog. There had been no apparent problems prior to the upgrade.
Mouse and keyboard both work when booted into recovery at the GRUB menu (select Ubuntu 20.04.xx recovery -> select resume, then yes). Disabling autologin also results in correct mouse and keyboard operation. In both cases, CTRL-ALT-DEL causes normal shutdown dialog.
Hardware: Gigabyte Motherboard with AMD Ryzen 5 3600, 16GB RAM, Gigabyte RTX2060 graphics, Logitech M510 and K350 with a unifying receiver, and a gigabit network card.
Things I have tried so far:
- Re-install Ubuntu 20.04.1 from a USB disc image, but retaining home directory -> no difference, still broken
- Disable autologin -> mouse and keyboard work, but I'm a single user and I don't need nor want the login screen
- Install KDE -> keyboard and mouse work normally, even with autologin enabled
- Install LightDM -> same as for KDE
- Switch back to GNOME, reinstall NVIDIA drivers -> no difference, still broken
- Upgrade NVIDIA drivers to latest version from repo -> no difference, still broken
- Upgrade NVIDIA drivers from NVIDIA website -> no difference, still broken
- Revert to open source NVIDIA drivers -> Keyboard and mouse work, but opening GNOME-settings causes instant logout. System cannot be logged in without reboot.
- Adding NOMODESET to GRUB -> no difference, still broken.
I am basically out of options. I tried posting the issue as a bug on the GNOME bug tracker website, the response was an arrogant "not a GNOME issue", which it clearly is because GNOME is the only DM that has this problem.
Has anyone figured out what's causing this? I know I'm not the only one to run into it.