xubuntu 18.04 Prime render offload problem geforce 940 mx.

Hello dear helpers!!! i am trying to use prime render offload on acer-e5-575-g.

i have intel core i5-7200u and geforce 940mx.

i installed nvidia drivers 440, for linux xubuntu 18.04 lts

and i configured my xorg.conf so

Section "ServerLayout"
      Identifier "layout"
      Option "AllowNVIDIAGPUScreens"
      Screen 0 "iGPU"

    Section "Device"
      Identifier "iGPU"
      Driver "modesetting"

    Section "Screen"
      Identifier "iGPU"
      Device "iGPU"

after that, i rebooted my notebook and tried to run command:

sudo __NV_PRIME_RENDER_OFFLOAD=1 __GLX_VENDOR_LIBRARY_NAME=nvidia glxinfo | grep OpenGL

but i get an error

X Error of failed request:  BadValue (integer parameter out of range for operation)
  Major opcode of failed request:  152 (GLX)
  Minor opcode of failed request:  24 (X_GLXCreateNewContext)
  Value in failed request:  0x0
  Serial number of failed request:  39
  Current serial number in output stream:  40

i tried to use this answer https://devtalk.nvidia.com/default/topic/1068229/linux/problem-with-offloading-with-prime/

but, when i add this code

Section "Files"
    ModulePath "/usr/lib/xorg/modules"
    ModulePath "/usr/lib/nvidia/xorg"

and reboot system, i have black screen and startx got me an error about xorg can not be run in buffermode.

so i edit xorg with nano editor (deleted section files) and rebooted system

my system was load, but i haved again main error.

Please help me…