package mysql-server-5.5 5.5.50-0ubuntu0.14.04.1 failed to install/upgrade: subprocess installed post-installation script returned error exit status 1

I may have run

sudo service mysql stop

while upgrading. Can that be the cause of error?

ProblemType: Package
DistroRelease: Ubuntu 14.04
Package: mysql-server-5.5 5.5.50-0ubuntu0.14.04.1
ProcVersionSignature: Ubuntu 3.19.0-65.73~14.04.1-generic 3.19.8-ckt22
Uname: Linux 3.19.0-65-generic x86_64
NonfreeKernelModules: nvidia
ApportVersion: 2.14.1-0ubuntu3.21
Architecture: amd64
Date: Fri Jul 22 09:27:58 2016
DuplicateSignature: package:mysql-server-5.5:5.5.50-0ubuntu0.14.04.1:subprocess installed post-installation script returned error exit status 1
ErrorMessage: subprocess installed post-installation script returned error exit status 1
InstallationDate: Installed on 2015-09-11 (315 days ago)
InstallationMedia: Ubuntu 14.04.3 LTS "Trusty Tahr" - Beta amd64 (20150805)
Logs.var.log.daemon.log:

MySQLConf.etc.mysql.conf.d..keepme:
MySQLConf.etc.mysql.conf.d.mysqld.safe.syslog.cnf:
 [mysqld_safe]
 syslog
MySQLVarLibDirListing: ['performance_schema', 'ibdata1', 'mysql_upgrade_info', 'ib_logfile1', 'imoveis_development', 'ib_logfile0', 'mysql', 'debian-5.5.flag', 'activerecord_unittest', 'activerecord_unittest2']
ProcCmdline: BOOT_IMAGE=/boot/vmlinuz-3.19.0-65-generic root=UUID=03657881-2771-4980-be1d-ee52ad8664a9 ro quiet splash video.use_native_backlight=1
RelatedPackageVersions:
 dpkg 1.17.5ubuntu5.7
 apt 1.0.1ubuntu2.14
SourcePackage: mysql-5.5
Title: package mysql-server-5.5 5.5.50-0ubuntu0.14.04.1 failed to install/upgrade: subprocess installed post-installation script returned error exit status 1
UpgradeStatus: No upgrade log present (probably fresh install)