can't upgrade to 18.04 from 16.04

[vnd]

Updater cann't calculate needed changes

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: ubuntu-release-upgrader-core 1:16.04.25
ProcVersionSignature: Ubuntu 4.4.0-122.146-generic 4.4.117
Uname: Linux 4.4.0-122-generic x86_64
ApportVersion: 2.20.1-0ubuntu2.16
Architecture: amd64
CrashDB: ubuntu
CurrentDesktop: Unity
Date: Sun Apr 29 12:08:13 2018
InstallationDate: Installed on 2016-07-27 (640 days ago)
InstallationMedia: Ubuntu 16.04.1 LTS "Xenial Xerus" - Release amd64 (20160719)
PackageArchitecture: all
SourcePackage: ubuntu-release-upgrader
UpgradeStatus: Upgraded to xenial on 2018-04-29 (0 days ago)

[dino99 (9d9)]

First revert the 'padoka' packages to the genuine ones (downgrade) and similar 'third party' packages if they exist. Then try upgrading again, or do a fresh install.

[Brian Murray (brian-murray)]

Reviewing the files from your upgrade attempt you seem to have enabled a PPA that provides Xorg packages. This will prevent the upgrade as that PPA contains different versions of packages essential to Ubuntu. The page, https://launchpad.net/~xorg-edgers/+archive/ppa, contains details on to how to revert to the official Xorg packages for the xorg-edgers PPA. Instructions for reverting to official Xorg packages should be similar for the PPA that you have enabled.