Cannot upgrade Xubuntu from 16.10 to 17.04

[Nick]

Try to upgrade and get message (RUS):
"Не удалось рассчитать обновление системы

Обнаружена неразрешимая проблема при расчёте обновления.

 Это может быть вызвано тем, что:
 * Обновление до пре-релиза Ubuntu
 * Использование текущей пре-релиз версии Ubuntu
 * Неофициальное ПО, не предоставляемое Ubuntu

Если ничего из перечисленного не подходит, сообщите об этой ошибке, выполнив команду «ubuntu-bug ubuntu-release-upgrader-core» в терминале."

ProblemType: Bug
DistroRelease: Ubuntu 16.10
Package: ubuntu-release-upgrader-core 1:16.10.10
ProcVersionSignature: Ubuntu 4.8.0-46.49-generic 4.8.17
Uname: Linux 4.8.0-46-generic x86_64
ApportVersion: 2.20.3-0ubuntu8.2
Architecture: amd64
CrashDB: ubuntu
CurrentDesktop: XFCE
Date: Fri Apr 14 21:48:50 2017
PackageArchitecture: all
SourcePackage: ubuntu-release-upgrader
UpgradeStatus: Upgraded to yakkety on 2017-04-14 (0 days ago)
VarLogDistupgradeTermlog:

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Brian Murray (brian-murray)]

Please stop marking bugs as a duplicate of this bug! Not all upgrade issues have the same cause and you are creating more work for me to unduplicate the bugs.

[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.

[Nick (nick222-yandex)]

Thank You :)
But where I can see - what PPA must be remove?