I can reproduce this issue, too. When plug in the dock(with HDMI 4k monitor), the screen freeze and keyboard/touchpad won't work, but I still can ssh into the machine. Un-plug the dock, everything works again.
BTW, I found gnome-shell runs in 100% while the issue happened, and un- plug the dock the CPU usage of gnome-shell comes back to normal. -- You received this bug notification because you are a member of Ubuntu Desktop Bugs, which is subscribed to mutter in Ubuntu. https://bugs.launchpad.net/bugs/1970495 Title: Window manager freezes when plugging in USB-C dock with external monitor ([drm] *ERROR* mstb 00000000f21f0a30 port 1: DPCD read on addr 0x4b0 for 1 bytes NAKed) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1970495/+subscriptions -- desktop-bugs mailing list desktop-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/desktop-bugs
