Unable to start mysql: /var/log/mysql/error.log: Permission denied

Symptoms

• Plesk installed on Ubuntu or Debian is not accessible, mysql fail to be started, mysql status shows:

  # service mysql status
  mysqld[17337]: [ERROR] Could not open file ‘/var/log/mysql/error.log’ for error logging: Permission denied
  mysqld[17337]: 0 [ERROR] Aborting

Cause

Incorrect permissions are set to the mysql log file
/var/log/mysql/error.log
or/and to folders and subfolders of
/var/log/mysql/error.log
:

# ls -la /var/log/mysql/error.log
-rwxr-x— 1 mysql mysql 7958 nov. 29 15:46 /var/log/mysql/error.log
# ls -la /var/log | grep mysql | grep -v gz | grep -v .err | grep -v log
drw-r–r– 2 mysql mysql 4096 nov. 29 16:37 mysql
# ls -la /var | grep log
drw-rw-r– 19 root root 4096 Dec 1 11:30 log
# ls -la / | grep var
dr–r–r– 16 root root 4096 Nov 13 13:40 var

Resolution

1. Login to the server via SSH.
2. Set an owner, a group and permissions to the correct one:

   For MySQL:

   # chown mysql:adm /var/log/mysql/error.log
   # chown mysql:adm /var/log/mysql
   # chown root:syslog /var/log
   # chown root:root /var
   # chmod 0640 /var/log/mysql/error.log
   # chmod 0750 /var/log/mysql
   # chmod 0775 /var/log
   # chmod 0755 /var

   For Mariadb:

   # chown mysql:adm /var/log/mariadb/mariadb.log
   # chown mysql:adm /var/log/mariadb/
   # chown root:root /var/log/
   # chown root:root /var
   # chmod 0640 /var/log/mariadb/mariadb.log
   # chmod 0750 /var/log/mariadb/
   # chmod 0775 /var/log/
   # chmod 0755 /var