On one machine (Dell Latitude E7440) running Ubuntu 16.04, when I try to switch to a TTY (e.g. using Ctrl+Alt+F1 or
sudo chvt 1), nothing happens.
I keep seeing the last state of my graphical desktop instead of a TTY terminal login, although it is frozen and not accepting any input. Switching back to TTY7 using Ctrl+Alt+F7 brings the desktop back to life as expected.
Why can I not switch to a TTY terminal on this system? How can I diagnose and fix the issue?
$ lspci -k | grep -iEA4 '3d|vga|display' 00:02.0 VGA compatible controller: Intel Corporation Haswell-ULT Integrated Graphics Controller (rev 0b) DeviceName: Onboard IGD Subsystem: Dell Haswell-ULT Integrated Graphics Controller Kernel driver in use: i915 Kernel modules: i915