The package system is broken
If you are using third party repositories then disable them, since they are a common source of problems.
Now run the following command in a terminal: apt-get install -f
The following packages have unmet dependencies.
libegl1-mesa : Depends: libgl1-mesa-dri (= 10.5~git1411191810.9460cd~gd~t) but 10.4~git1411171930.920f87~gd~t is installed
libgbm1 : Depends: libgl1-mesa-dri (= 10.5~git1411191810.9460cd~gd~t) but 10.4~git1411171930.920f87~gd~t is installed
libgl1-mesa-dri : Breaks: libgl1-mesa-dri:i386 (!= 10.4~git1411171930.920f87~gd~t) but 10.5~git1411191810.9460cd~gd~t is installed
libgl1-mesa-dri:i386 : Breaks: libgl1-mesa-dri (!= 10.5~git1411191810.9460cd~gd~t) but 10.4~git1411171930.920f87~gd~t is installed
libgl1-mesa-glx : Depends: libgl1-mesa-dri (= 10.5~git1411191810.9460cd~gd~t) but 10.4~git1411171930.920f87~gd~t is installed
E: Error, pkgProblemResolver::Resolve generated breaks, this may be caused by held packages.
E: Unable to correct dependencies
I'm on Ubuntu 14.04. I was using the update drivers from Updated and Optimized Open Graphics Drivers , so the first thing I did was remove that PPA, but this doesn't seem to have helped.
EDIT: I've followed these instructions, but to no avail:
How do I resolve unmet dependencies after adding a PPA?
How to Fix the "Package System is Broken" Error on Ubuntu 11.04 / 10.10 / 10.04
Package system is broken. How to fix it?
Running these commands achieves nothing:
sudo apt-get clean
sudo apt-get -f install
sudo apt-get update
I don't have synaptic installed and when I try to install it, or remove packages using sudo apt-get remove --dry-run
I just get more errors about unmet dependencies. I've been using Ubuntu for years and have always been able to resolve problems like this in the past, but something is eluding me here.