Solving a “communications link failure” with JDBC and MySQL [duplicate]

Answer 1

In my case,

1. Change the remote machine mysql configuration at /etc/mysql/my.cnf: change bind-address = 127.0.0.1 to #bind-address = 127.0.0.1

2. On the remote machine, change mysql user permissions with GRANT ALL PRIVILEGES ON *.* TO 'user'@'%' IDENTIFIED BY 'password';

3. IMPORTANT: restart mysql on the remote machine: sudo /etc/init.d/mysql restart

Answer 2

I just restarted MySQL (following a tip from here: https://stackoverflow.com/a/14238800) and it solved the issue.

I had the same issue on MacOS (10.10.2) and MySql (5.6.21) installed via homebrew.

The confusing thing was that one of my apps connected to the database fine and the other did not.

After trying many things on the app that threw the exception com.mysql.jdbc.CommunicationsException as suggested by the accepted answer of this question to no avail, I was surprised that restarting MySQL worked.

The cause of my issue might have been the following as suggested in the answer in the aforementioned link:

Are you using connection pool ? If yes, then try to restart the server. Probably few of the connections in your connection pool are in closed state.

Answer 3

I found the solution

since MySQL need the Localhost in-order to work.

go to /etc/network/interfaces file and make sure you have the localhost configuration set there:

auto lo
iface lo inet loopback

NOW RESTART the Networking subsystem and the MySQL Services:

sudo /etc/init.d/networking restart

sudo /etc/init.d/mysql restart

Try it now

Answer 4

In phpstorm + vagrant autoReconnect driver option helped.

Answer 5

Setting the bind-address to the server's network IP instead of the localhost default, and setting privileges on my user worked for me.

my.cnf:

bind-address = 192.168.123.456

MySql Console:

GRANT ALL PRIVILEGES ON dbname.* to username@'%' IDENTIFIED BY 'password';

Answer 6

It happens (in my case) when there is not enough memory for MySQL. A restart fixes it, but if that's the case consider a nachine with more memory, or limit the memory taken by jvms