A recent X update broke VirtualBox guest additions (vboxvideo driver version
mismatch, desktop won't start). This fixes it.
Here is the error log:
(II) "glx" will be loaded by default.
(II) LoadModule: "glx"
(II) Loading /nix/store/kzvmnjlps51q4piqmwr7zbmxcg2z9vgk-xorg-server-1.13.4/lib/xorg/modules/extensions/libglx.so
(II) Module glx: vendor="X.Org Foundation"
compiled for 1.13.4, module version = 1.0.0
ABI class: X.Org Server Extension, version 7.0
(==) AIGLX enabled
Loading extension GLX
(II) LoadModule: "vboxvideo"
(II) Loading /nix/store/4kbxi00h8xsmfgbws2qqh674lcfp03h6-VirtualBox-GuestAdditions-4.2.14-3.2.46/lib/xorg/modules/drivers/vboxvideo_drv.so
(II) Module vboxvideo: vendor="Oracle Corporation"
compiled for 10.12.0, module version = 1.0.1
Module class: X.Org Video Driver
ABI class: X.Org Video Driver, version 12.0
(EE) module ABI major version (12) doesn't match the server's version (13)
(II) UnloadModule: "vboxvideo"
(II) Unloading vboxvideo
(EE) Failed to load module "vboxvideo" (module requirement mismatch, 0)
(II) LoadModule: "vboxmouse"
(WW) Warning, couldn't open module vboxmouse
(II) UnloadModule: "vboxmouse"
(II) Unloading vboxmouse
(EE) Failed to load module "vboxmouse" (module does not exist, 0)
(EE) No drivers available.
Fatal server error:
no screens found