cp: cannot overwrite directory '/var/lib/mysql-upgrade/DATADIR.link/mysql' with non-directory

[Chris]

I used mariadb instead of mysql-server. The auto dost-upgrade failed with an error, but after a reboot I just removed "mysql-server" package, installed mariadb-server and now it works.

ProblemType: Package
DistroRelease: Ubuntu 16.04
Package: mysql-server-5.7 (not installed)
ProcVersionSignature: Ubuntu 4.2.0-35.40-generic 4.2.8-ckt5
Uname: Linux 4.2.0-35-generic x86_64
ApportVersion: 2.19.1-0ubuntu5
Architecture: amd64
Date: Sun May 1 22:08:41 2016
DpkgTerminalLog:
 Vorbereitung zum Entpacken von .../mysql-server-5.7_5.7.12-0ubuntu1_amd64.deb ...
 invoke-rc.d: Unit mysql.service is masked
 cp: cannot overwrite directory '/var/lib/mysql-upgrade/DATADIR.link/mysql' with non-directory
 dpkg: Fehler beim Bearbeiten des Archivs /var/cache/apt/archives/mysql-server-5.7_5.7.12-0ubuntu1_amd64.deb (--unpack):
  Unterprozess neues pre-installation-Skript gab den Fehlerwert 1 zurück
DuplicateSignature: package:mysql-server-5.7:(not installed):Unterprozess neues pre-installation-Skript gab den Fehlerwert 1 zurück
ErrorMessage: Unterprozess neues pre-installation-Skript gab den Fehlerwert 1 zurück
InstallationDate: Installed on 2015-11-16 (167 days ago)
InstallationMedia: Ubuntu-Server 15.10 "Wily Werewolf" - Release amd64 (20151021)
RelatedPackageVersions:
 dpkg 1.18.4ubuntu1
 apt 1.2.10ubuntu1
SourcePackage: mysql-5.7
Title: package mysql-server-5.7 (not installed) failed to install/upgrade: Unterprozess neues pre-installation-Skript gab den Fehlerwert 1 zurück
UpgradeStatus: Upgraded to xenial on 2016-05-01 (0 days ago)

[Launchpad Janitor (janitor)]

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