package mysql-server-5.7 5.7.11-0ubuntu6 failed to install/upgrade: subprocess installed post-installation script returned error exit status 1

[Marko-macmilan]

upgrading from 15.10 ubuntu server on x86 machine. do-release-upgrade route.

ProblemType: Package
DistroRelease: Ubuntu 16.04
Package: mysql-server-5.7 5.7.11-0ubuntu6
ProcVersionSignature: Ubuntu 4.2.0-35.40-generic 4.2.8-ckt5
Uname: Linux 4.2.0-35-generic i686
ApportVersion: 2.20.1-0ubuntu2
Architecture: i386
Date: Mon Apr 25 01:40:25 2016
ErrorMessage: subprocess installed post-installation script returned error exit status 1
InstallationDate: Installed on 2012-11-19 (1252 days ago)
InstallationMedia: Ubuntu-Server 12.10 "Quantal Quetzal" - Release i386 (20121017.2)
Logs.var.log.daemon.log:

MySQLConf.etc.mysql.conf.d.mysql.cnf: [mysql]
MySQLConf.etc.mysql.conf.d.mysqld_safe_syslog.cnf:
 [mysqld_safe]
 syslog
MySQLConf.etc.mysql.conf.d.mysqldump.cnf:
 [mysqldump]
 quick
 quote-names
 max_allowed_packet = 16M
MySQLConf.etc.mysql.mysql.conf.d.mysqld_safe_syslog.cnf:
 [mysqld_safe]
 syslog
MySQLVarLibDirListing: ['ibdata1', 'ang@002drest', 'ib_logfile0', 'ib_logfile1', 'kravica', 'opub@002dks@002drs', 'debian-5.5.flag', 'ea@002dstart', 'govcms@002dks@002drs', 'mysql_upgrade_info', 'ks@002drs@002dold', 'ea@002dshop', 'auto.cnf', 'dru@002dks@002drs', 'studiod_visavis', 'wp', 'visavis', 'debian-5.6.flag', 'test@002dmarko_development', 'performance_schema', 'debian-5.7.flag', 'ks@002drs', 'ib_buffer_pool', 'mysql', 'phpmyadmin', 'sys']
ProcCmdline: BOOT_IMAGE=/vmlinuz-4.2.0-35-generic root=UUID=4381903c-d6fd-48d8-a95f-32f870604629 ro
RelatedPackageVersions:
 dpkg 1.18.4ubuntu1
 apt 1.2.10ubuntu1
SourcePackage: mysql-5.7
Title: package mysql-server-5.7 5.7.11-0ubuntu6 failed to install/upgrade: subprocess installed post-installation script returned error exit status 1
UpgradeStatus: Upgraded to xenial on 2016-04-24 (0 days ago)