MySql server PID not found

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.

I upgraded my Mac OS to 10.9.3 and encountered the above problem on mysql.server restart

The following fixed my problem

sudo chmod -R o+rwx /usr/local/var/mysql/sudo chown -R mysql /usr/local/var/mysql/sudo mysql.server restart

First of all make sure that which folder/file is not exist in /var/run/mysqld/mysqld.pid

if dir not exists then create it as:

sudo mkdir -p /var/run/mysqld/

if mysqld.pid is not exists then create it as:

sudo touch /var/run/mysqld/mysqld.pid

change ownership as:

sudo chown mysql:mysql -R /var/run/mysqldchmod 775 -R /var/run/mysqld

restart mysql service

sudo service mysql restart