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

Answer 1

I know this is an old thread but I have tried numerous things and fixed my issue using the following means..

I'm developing a cross platform app on Windows but to be used on Linux and Windows servers.

A MySQL database called "jtm" installed on both systems. For some reason, in my code I had the database name as "JTM". On Windows it worked fine, in fact on several Windows systems it flew along.

On Ubuntu I got the error above time and time again. I tested it out with the correct case in the code "jtm" and it works a treat.

Linux is obviously a lot less forgiving about case sensitivity (rightly so), whereas Windows makes allowances.

I feel a bit daft now but check everything. The error message is not the best but it does seem fixable if you persevere and get things right.

Answer 2

In my case it was an idle timeout, that caused the connection to be dropped on the server. The connection was kept open, but not used for a long period of time. Then a client restart works, while I believe a reconnect will work as well.

A not bad solution is to have a daemon/service to ping the connection from time to time.

Answer 3

The resolution provided by Soheil was successful in my case.

To clarify, the only change I needed to make was with MySQL's server configuration;

bind-address = **INSERT-IP-HERE**

I am using an external MySQL server for my application. It is a basic Debian 7.5 installation with MySQL Server 5.5 - default configuration.

IMPORTANT:

Always backup the original of any configuration files you may modify. Always take care when elevated as super user.

File

/etc/mysql/my.cnf

Line

bind-address        = 192.168.0.103 #127.0.0.1

Restart your MySQL Server service:

/usr/sbin/service mysql restart

As you can see, I simply provided the network IP of the server and commented out the default entry. Please note that simply copy and paste my solution will not work for you, unless by some miracle our hosts share the same IP.

Thanks @ Soheil

Answer 4

If you are using hibernate, this error can be caused for keeping open a Session object more time than wait_timeout

I've documented a case in here for those who are interested.

Answer 5

For me the solution was to change in the conf file of mysql server the parameter bind-address="127.0.0.1" or bind-address="x.x.x.x" to bind-address="0.0.0.0". Thanks.

Answer 6

Had the same. Removing port helped in my case, so I left it as jdbc:mysql://localhost/