Cannot switch TTY with Ctrl + Alt + F1…Fn (Ubuntu)

Just copying what Lswest wrote more than two years ago: if your TTY switching is not working, and you have a custom ~/.Xmodmap, make sure your mappings for the function keys in it are as follows:

keycode  67 = F1 F1 F1 F1 F1 F1 XF86Switch_VT_1
keycode  68 = F2 F2 F2 F2 F2 F2 XF86Switch_VT_2
keycode  69 = F3 F3 F3 F3 F3 F3 XF86Switch_VT_3
keycode  70 = F4 F4 F4 F4 F4 F4 XF86Switch_VT_4
keycode  71 = F5 F5 F5 F5 F5 F5 XF86Switch_VT_5
keycode  72 = F6 F6 F6 F6 F6 F6 XF86Switch_VT_6
keycode  73 = F7 F7 F7 F7 F7 F7 XF86Switch_VT_7
keycode  74 = F8 F8 F8 F8 F8 F8 XF86Switch_VT_8
keycode  75 = F9 F9 F9 F9 F9 F9 XF86Switch_VT_9

(And, in case Ctrl + Alt + Backspace also doesn’t work:

keycode  22 = BackSpace Terminate_Server BackSpace Terminate_Server BackSpace

but you’ll also need to have it enabled in Keyboard Layout Options, under “Key sequence to kill the X server”.)