MySQL 5.5 starts and then instantly stops

I'm cross copying this post from superuser, it basically fixes your problem.

I used The following guide to install 5.5 on Ubuntu 11.04: http://www.ovaistariq.net/490/a-step-by-step-guide-to-upgrading-to-mysql-5-5/

Everything worked perfectly except one of the final steps, launching mysql:

mysqld --skip-grant-tables --user=mysql

Was giving me the following message and then shutting down:

[ERROR] Can't find messagefile '/usr/share/errmsg.sys'

After some googling I found the solution to be adding the following flag:

--lc-messages-dir="/usr/local/mysql/share/english/"

To launch it and have it actually work, I used the following command:

 mysqld --skip-grant-tables --user=mysql --lc-messages-dir="/usr/local/mysql/share/english/"

MySQL 5.5 has some great new features that solved a partitioning issue for me; partitioning via a varchar.

Good luck!

From your log:

120210 2:33:23 [ERROR] Can't find messagefile '/usr/share/errmsg.sys'

That seems to be the issue. Check to see if the file is there.

Check to see if the file /usr/local/mysql/share/english/errmsg.sys exists and then:

cp /usr/local/mysql/share/english/errmsg.sys /usr/share/errmsg.sys

Make sure the new /usr/share/errmsg.sys file has permissions for MySQL to access it and try restarting.

From the link above, it seems this just happened when the user restarted the machine. If your machine was rebooted, it might for some reason have deleted the file. Why would it do that? I have no idea, unfortunately.

Better not copy files to the fallback directory. Instead, either specify the parameter in the command line, or add the following to my.ini / my.cnf:

[mysqld]
lc_messages_dir = /usr/local/mysql/share

More details here.