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com.mysql.cj.jdbc.exceptions.communicationsexception communications link failure

by | May 16, 2022

com.mysql.cj.jdbc.exceptions.communicationsexception communications link failure can be resolved with a little help from our experts.

At Bobcares, we offer solutions for every query, big and small, as a part of our Server Management Services.

Let’s take a look at how our Support Team is ready to help customers resolve com.mysql.cj.jdbc.exceptions.communicationsexception communications link failure message.

Resolved: com.mysql.cj.jdbc.exceptions.communicationsexception communications link failure

Have you been running into communications link failure messages?

SQLException: Connection refused or Connection timed out

Or

CommunicationsException: Communications link failure

If yes, it usually means that the database is not reachable. According to our MySQL Support Techs, the communications link failure message may be due to one of the following reasons:

 

com.mysql.cj.jdbc.exceptions.communicationsexception communications link failure

  • The wrong IP address of the JDBC URL
  • Unrecognized hostname in JDBC URL
  • Missing or inaccurate port number in DNS server
  • DB server is down
  • TCP/IP connections not accepted by DB server
  • DB server does not have any more connections

Fortunately, we can resolve the communications link failure message with these steps:

  1. To begin with, verify and test with the ping command.
  2. Next, refresh DNS. Alternatively, we can use the IP address in JDBC URL instead.
  3. Verify this according to my.cnf of MySQL DB.
  4. After that, the database and check if mysqld started without the –skip-networking option.
  5. Then, restart the database and fix the code to close the connections.
  6. Next, disable the firewall or enable the firewall to allow the port. We can add the TLS protocol to the connection string
    jdbc:mysql://localhost:3306/database_name?enabledTLSProtocols=TLSv1.2

Furthermore, we can update the IP address with these steps to resolve the communications link failure message:

    1. First, open /etc/mysql/my.cnf file.
    2. Then, change the bind-address as bind-address = 0.0.0.0.

Alternatively, restart mysql daemon and mysql services to resolve the failure message.

However, if you are still running into communications link failure message, our MySQL Support Techs are just a click away.

[Need assistance with another query? We are available 24/7.]

Conclusion

In a nutshell, our skilled Support Engineers at Bobcares demonstrated how to resolve com.mysql.cj.jdbc.exceptions.communicationsexception communications link failure message.

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2 Comments

  1. holdemgun

    I utilize the com.mysql.cj.jdbc.Driver connector and use MySQL 8.1 on Windows 10 machine. I added to my.ini “bind-address=”0.0.0.0” and I can succesfully connect from my Java program to jdbc:mysql://localhost:3306/my_db url. But I can’t connect to jdbc:mysql://222.2.222.222:3306/my_db where instead of 222.2.222.222 is my IP. Help please.

    Now, moving on to a question that might sound a bit basic:
    My computer is connected to the internet via a WiFi router that serves multiple devices. Is it feasible for a MySQL Server, reachable from the internet, to be hosted through this WiFi router? Could this potentially be the root of the issue?

    Reply
    • Hiba Razak

      Hi,
      Please contact our support team via live chat(click on the icon at right-bottom).

      Reply

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