MySQL: Can't create/write to file '/tmp/#sql_3c6_0.MYI' (Errcode: 2) - What does it even mean?

Question

For some reason my production DB decided to spew out this message. All application calls fail to the DB with the error:

PreparedStatementCallback; SQL [ /*lo         


        

Answer 1

For me this issue came after a long period of not using mysql nor the webserver. So I was sure that my settings where correct; Simply restarting the service fixes this issue; The weird part about the issue is that one can still connect to the database, and even query/add tables using the mysql tool. for example :

mysql -u root -p

I restarted using :

systemctl start mysqld.service

or service mysqld restart or /etc/init.d/mysqld restart

Note : depending on the machine/environment on of these commands should restart the service.