Can't alter display settings. Trying to configure External Monitor

Question

I just bought an external monitor to go with my laptop. The computer is an HP Elitebook 6930p. I'm using Ubuntu 12.04 with the Cinnamon desktop.

The external monitor actually works fine right out of the box. As of now it is acting as an extension of the laptop screen. My problem is that I want to configure Ubuntu to display ONLY on the external monitor, or at least show the launch bar and start menu on the monitor, as I would like to close the computer and still be able to use it. *Unfortunately I can't make ANY changes to the display settings. Even if I don't change anything, the act of hitting the "Apply" button brings this message:

"Failed to apply configuration: %s

GDBus.Error:org.freedesktop.DBus.Error.UnknownMethod: No such interface `org.gnome.SettingsDaemon.XRANDR_2' on object at path /org/gnome/SettingsDaemon/XRANDR"

Obviously I cannot choose to "Mirror Displays". I cannot change ANY display settings. Any solution or workaround would be greatly appreciated.

Solution

The problem is that you're running the Ubuntu display settings configuration editor rather the Cinnamon one. Apparently you now have to use Cinnamon's. It's confusing because they look almost identical. To make sure you're launching the Cinnamon one, navigate to it from the Cinnamon Menu launcher thing (Menu->Preferences->Displays).

Comments

[Wilf]

Search for monitors.xml in .config. You should be able to open it using gedit .config/monitors.xml in terminal. Edit it, or copy and remove it and see what happens (You may need to reboot, logout and login again or something)

[Seth Balmore]

Thankyou. I tried editing the document by making the VGA output read "Yes" as my primary monitor. All I had to do was restart the computer and everything worked perfectly. It's not a solution, but certainly an adequate workaround. So thankyou for taking the time to help me.

[Seth Balmore]

As a sidenote, the changes I made to "monitors.xml" are reflected in the display settings. My external monitor is now shown as my primary monitor in the animated representation.

[Seth Balmore]

Also I think the problem may lie in how the Cinnamon desktop is integrated into Ubuntu. Cinnamon comes with its own system settings, but the system settings from the stock Unity desktop are still present. For instance, I can change the desktop wallpaper with the Cinnamon System Settings OR the normal System Settings. Using both results in a conflict and confuses the computer. I suspect something similar is happening with the display settings because there is only ONE "Displays" menu - for the Unity desktop - but NO menu for my current Cinnamon desktop.

[Wilf]

Cinnamon is good, but I think Unity and Cinnamon both originated from GNOME. I tried Cinnamon, and it is good, but I ended up with TWO lock screens (at the same time). Atleast you got the monitors working again. N.B. Be careful, as some of the settings dialogues are so similar it can get very confusing.

[Admin]

I too, started receiving this error (see OP). I have my Thinkpad W500 (Ubuntu 12.04 with Cinnamon) set to do nothing when the lid closes, however, every time I close the lid and reopen the lid, my external display toggles between mirrored and extended. YMMV