I've just installed Ubuntu MATE 18.04 on a laptop and have a dual monitor setup, both displays worked out of the box and the native display even went off on boot. I now need to use 1366x768 resolution on one of the displays but it is not an option. I've added a resolution but the resulting resolution is not correct I accidentally added 1368x768
Trying again gives error:
cvt 1366 768 60
sudo xrandr --newmode "1366x768_60.00" 85.25 1366 1440 1576 1784 768 771 781 798 -hsync +vsync
X Error of failed request: BadName (named color or font does not exist) Major opcode of failed request: 140 (RANDR) Minor opcode of failed request: 16 (RRCreateMode) Serial number of failed request: 31 Current serial number in output stream: 311 Answer
To add a new mode to an output requires several commands in sequence, like so:
# create and name a new mode: "1366x768-0"
xrandr --newmode "1366x768-0" 75.61 1366 1406 1438 1574 768 771 777 800 -hsync -vsync
# attach the new mode to an output (VGA1)
xrandr --addmode VGA1 "1366x768-0"
# turn on the output using the new mode
xrandr --output VGA1 --mode "1366x768-0"The reason for the error messages in the question is mode parameters cannot be changed. Use a new name (such as "1366x768-1") or remove the added mode. The sequence of commands to remove a mode follow:
# turn off the output
xrandr --output VGA1 --off
# detach the mode from the output
xrandr --delmode VGA1 "1366x768-0"
# remove the mode
xrandr --rmmode "1366x768-0"Changes to xrandr don't survive reboot. To make settings persist, ubstitute parameters as appropriate for your setup and save into a script in /usr/local/bin and add it to Startup Applications. Then it will be run every time you log in. You might like to add it at boot up, rather than login.
