unmet dependencies for synaptics touchpad driver

Question

I have Ubuntu 14.04.2 installed on a Lenovo S21e-20. To get things like two-finger-scrolling or suspending the touchpad during typing, I wanted to install xserver-xorg-input-synaptics but installation fails with two unmet dependencies due to held broken packages (command outputs below). All those packages should be installed already by default (my installation is fresh, this is the first thing I do on this system after wi-fi driver installation).

Output of sudo apt-get install xserver-xorg-input-synaptics:

Reading package lists... Done
Building dependency tree       
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies.
 xserver-xorg-input-synaptics : Depends: xorg-input-abi-20
                                Depends: xserver-xorg-core (>= 2:1.14.99.902)
E: Unable to correct problems, you have held broken packages.

Output of sudo apt-get install xorg-input-abi-20:

Reading package lists... Done
Building dependency tree       
Reading state information... Done
Note, selecting 'xserver-xorg-core' instead of 'xorg-input-abi-20'
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies.
 libcheese-gtk23 : Depends: libclutter-gtk-1.0-0 (>= 0.91.8) but it is  not going to be installed
               Depends: libcogl15 (>= 1.15.8) but it is not going to be installed
 libcheese7 : Depends: libclutter-gst-2.0-0 (>= 0.10.0) but it is not going to be installed
              Depends: gstreamer1.0-clutter but it is not going to be installed
 libclutter-1.0-0 : Depends: libcogl-pango15 (>= 1.15.8) but it is not going to be installed
                    Depends: libcogl15 (>= 1.15.8) but it is not going to be installed
E: Error, pkgProblemResolver::Resolve generated breaks, this may be caused by held packages.

Trying to install xserver-xorg-core aborts with a similar problem, i.e. the same unmet dependencies.

I tried sudo apt-get clean, sudo apt-get update, sudo dpkg --configure -a and sudo apt-get -f install, but all those did not solve the problem. No held packages are shown.

Trying to install the unment dependencies of xserver-xorg-core directly, shows that they are already installed.

How can I resolve this?

Solution

A good way to solve these problems is to use aptitude.

sudo apt-get install aptitude
sudo aptitude update
sudo aptitude install xserver-xorg-input-synaptics

Now several ways to solve the problem will be proposed by aptitude:

Choose the solution that uninstalls the least packets. Write down what packages are removed. Install the packages again if needed.

Comments

[Byte Commander]

Could you please add the full command outputs instead of just quoting small snippets? Thank you!

[Till B]

hmm. aptitude talks about a couple of colliding dependencies. As a recommendation it wants to remove ubuntu-desktop, but I am not so certain about that...

[A.B.]

ubuntu-desktop is only a meta package. You can reinstall ubuntu-desktop later.

[A.B.]

@TillB Choose the solution that uninstalls the least packets. Write down what packages are removed. Install the packages again, you still need.

[A.B.]

@TillB Were you satisfied with my answer? Then give me a upvote (∧). If I could solve your problem, then it would be nice if you'd mark my answer (✓). ;)

[Till B]

I am still working on it, currently it does not boot again

[A.B.]

@TillB Error messages?

[Till B]

none, just does not boot, not even showing GRUB

[A.B.]

@TillB What packages you removed?

[Till B]

ubuntu-desktop and a couple of xserver-xorg packages, I do not have a full list

[A.B.]

Something will start yet. Works Ctrl-Alt-F1 or Ctrl-Alt-F2 etc.?

[Till B]

no, does not. When it boots, I shortly see the boot splash, then the screen is on, but black

[A.B.]

GRUB menu will appear if you press and hold Shift during loading Grub. Try it. Then boot the recovery mode.

[Till B]

Let us continue this discussion in chat.

[Pilot6]

@A.B. This is a wrong command for 14.04.x. In 14.04.3 it is xserver-xorg-input-synaptics-lts-vivid, etc. And there is no need to install synaptics, since it is installed by default. But if you want, then check which HWE xorg is there. And the correct way is to install xserver-xorg-input-all-lts-xxxxx.

[V. Sambor]

I tried this commands and I felt into same problem ... ubuntu did not want to boot any more... just black screen after 'ubuntu logo' ... Now I tried different distribution, I installed linux mint 17, but touchpad problem still persist. I don't knoww how to make this driver work....I'm new to linux