MySql server PID not found

Question

I have CentOS 6.4 with NGINX. When I try to `start/stop/restart` mysql server `(/etc/init.d/mysqld restart)` I get this error: ``` MySQL server PID file could not be found! [FAILED] Starting MySQL..The server quit without updating PID file ([FAILED]/mysql/mysqld.pid). ``` What can I do to solve this problem? Thanks!

Accepted Answer

I got the same error on a CentOS 6.3 where I upgraded MySQL to 5.6.14 but I kept the old my.cnf file. After upgrade, MySQL did not start anymore, giving me the same error as you described.

The problem was that I had this setting in my.cnf:

```
table_cache=2048
```

According to this link table_cache renamed table_open_cache..

"Seem like in 5.5 the system variable table_cache was renamed table_open_cache.. In 5.6 mysqld fails if it finds an unknown variable this means that upgrades from versions earlier than 5.5 can have problems if table_cache is specified in my.cnf."

After I changed the above line to

```
table_open_cache=2048
```

MySQL started perfectly.

So, in the case you have MySQL 5.5+ (and maybe an older my.cnf), I suggest you to do the following:

- remove my.cnf from /etc folder and try to start MySQL

- if MySQL starts, the the problem is in my.cnf. Comment/uncomment all the settings one by one in order to see which is causing the problem.

Hope this helps.

MySql server PID not found

Solution

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