If you are trying to upgrade from MySQL server from 5.1 to 5.5 on debian and if you are getting below error then you can try this steps to resolve the issue for you:
Setting up mysql-server-core-5.5 (5.5.30-1~dotdeb.0) … Setting up mysql-server-5.5 (5.5.30-1~dotdeb.0) … Installing new version of config file /etc/mysql/debian-start … Installing new version of config file /etc/init.d/mysql … Installing new version of config file /etc/logrotate.d/mysql-server … Stopping MySQL database server: mysqld. Starting MySQL database server: mysqld . . . . . . . . . . . . . . failed! invoke-rc.d: initscript mysql, action “start” failed. dpkg: error processing mysql-server-5.5 (–configure): subprocess installed post-installation script returned error exit status 1 dpkg: dependency problems prevent configuration of mysql-server: mysql-server depends on mysql-server-5.5; however: Package mysql-server-5.5 is not configured yet. dpkg: error processing mysql-server (–configure): dependency problems – leaving unconfigured configured to not write apport reports configured to not write apport reports Errors were encountered while processing: mysql-server-5.5 mysql-server E: Sub-process /usr/bin/dpkg returned an error code (1)
Steps to resolve the issue while upgrading MySQL Server:
Take a look at /var/log/syslog and check what errors are you getting:
Quick fix for the below errors:
Error 1: [Warning] The syntax '--log-slow-queries' is deprecated and will be removed in a future release. Please use '--slow-query-log'/'--slow-query-log-file' instead.
Correct syntax for slow queries log in MySQL 5.5:
slow_query_log_file = /your/path/slowqueries.log
Error 2: [Warning] ignore-builtin-innodb is deprecated and will be removed in future releases.
The built-in InnoDB storage engine within MySQL is the original form of distribution for the storage engine. Contrast with the InnoDB Plugin. Starting with MySQL 5.5, the InnoDB Plugin is merged back into the MySQL code base as the built-in InnoDB storage engine (known as InnoDB 1.1).
This distinction is important mainly in MySQL 5.1, where a feature or bug fix might apply to the InnoDB Plugin but not the built-in InnoDB, or vice versa.
Simply remove this line if you have in your my.cnf
Error 3: [ERROR] Couldn't load plugin named 'innodb' with soname 'ha_innodb_plugin.so'.
Remove below line from your old my.cnf
Error 4: /usr/sbin/mysqld: unknown variable 'default-character-set=utf8'
Use charset_name as the default character set. This option is deprecated in favor of --character-set-server. See Section 9.5, “Character Set Configuration”. --default-character-set was removed in MySQL 5.5.3.
Error 5: If you are getting permissions errors you can always start MySQL Server using this:
/usr/sbin/mysqld --skip-grant &
Don't panic if your MySQL server doesn't start after upgrade. Just keep checking logs and see where is the issue and try to resolve it. Took me a few minutes to figure the issue out but logs are your best friend during upgrade.
Note: Never forget to take back ups before upgrade.