package snapd 2.21~14.04.2 failed to install/upgrade: subprocess installed post-installation script returned error exit status 1

[Francesco Morelli]

During uprading I've occurred this bug

ProblemType: Package
DistroRelease: Ubuntu 16.10
Package: snapd 2.21~14.04.2
ProcVersionSignature: Ubuntu 4.8.0-34.36-generic 4.8.11
Uname: Linux 4.8.0-34-generic x86_64
NonfreeKernelModules: nvidia_uvm nvidia_drm nvidia_modeset nvidia
ApportVersion: 2.20.3-0ubuntu8.2
Architecture: amd64
Date: Sun Jan 22 12:03:26 2017
DuplicateSignature:
 package:snapd:2.21~14.04.2
 Installing new version of config file /etc/X11/Xsession.d/65snappy ...
 Failed to enable unit: No such file or directory
 dpkg: error processing package snapd (--configure):
  subprocess installed post-installation script returned error exit status 1
ErrorMessage: subprocess installed post-installation script returned error exit status 1
InstallationDate: Installed on 2016-10-25 (88 days ago)
InstallationMedia: Ubuntu 14.04 LTS "Trusty Tahr" - Release amd64 (20140417)
RelatedPackageVersions:
 dpkg 1.18.10ubuntu1
 apt 1.3.3
SourcePackage: snapd
Title: package snapd 2.21~14.04.2 failed to install/upgrade: subprocess installed post-installation script returned error exit status 1
UpgradeStatus: No upgrade log present (probably fresh install)

[Michael Vogt (mvo)]

Here is the error:

Failed to enable unit: No such file or directory
dpkg: error processing package snapd (--configure):
 subprocess installed post-installation script returned error exit status 1

Did you (or something on the system) remove snapd releated files manually?