Unable to install Python 3

[PierreSoulier]

Hello!

I'm unable to install Python 3 as i get this:

sudo apt-get install python3

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:
 gsettings-desktop-schemas : Breaks: mutter (< 3.19.92) but 3.18.3-0ubuntu2 is to be installed
E: Error, pkgProblemResolver::Resolve generated breaks, this may be caused by held packages.

Do you have any idea?