Ubuntu – Failed to get size of gamma for output default when trying to add new screen resolution

command linedisplay-resolutiongraphicsnvidiaxrandr

I'm trying to adjust resolution on my new MSI GT70 2OC. In settings, only one resolution is available: 1920×1080. This is fine, except that I need to decrease the resolution and make it more rectangular for the laptop to work well with my old PL-550 tablet.

Here's what I do:

cvt 1200 1000 60
    # 1200x1000 59.91 Hz (CVT) hsync: 62.19 kHz; pclk: 99.50 MHz
    Modeline "1200x1000_60.00"   99.50  1200 1280 1400 1600  1000 1003 1013 1038 -hsync +vsync
sudo xrandr --newmode "1200_1000_60"   99.50  1200 1280 1400 1600  1000 1003 1013 1038 -hsync +vsync
    xrandr: Failed to get size of gamma for output default

How do I get past this step?

UPDATE
Here's the output of xrandr:

xrandr: Failed to get size of gamma for output default
Screen 0: minimum 1920 x 1080, current 1920 x 1080, maximum 1920 x 1080
default connected primary 1920x1080+0+0 0mm x 0mm
   1920x1080       0.0*

Best Answer

You don't need sudo to register the new mode with xrandr, try without sudo. Then you'll have to apply the new resolution with:

xrandr --addmode <your_connection_type> 1200x1000_60.00

Where <your_connection_type> is usually VGA1, DP1 or HDMI1. Check the output of xrandr to know the exact name of the connected output.

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