Root exception is com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure

RE: Root exception is com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure

SRINIVAS M — Sat, 06 Apr 2024 11:24:31 GMT

Verify Connectivity: --->Check if the database server is running and accessible from your Appian server (try pinging the database server's IP address) and --->Ensure there's no firewall blocking connections on the database port (usually 3306).
Check Credentials:-->custom.properties: Make sure the database URL, username, and password are correct.-->tomcatResource.xml: Verify the data source name matches custom.properties.
Address SSL Warning:-->Review your MySQL configuration and client settings if SSL is required. You may need to provide a truststore.

RE: Root exception is com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure

David Jimenez — Fri, 05 Apr 2024 20:17:26 GMT

If the problem were related with drivers, the error would be different

RE: Root exception is com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure

Hishore Nallasivam — Fri, 05 Apr 2024 07:22:22 GMT

You can also check the database drivers which you are using on Appian to connect the database.

docs.appian.com/.../System_Requirements.html

RE: Root exception is com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure

David Jimenez — Thu, 04 Apr 2024 21:49:16 GMT

If you get a SQLException: Connection refused or Connection timed out or a MySQL specific CommunicationsException: Communications link failure, then it means that the DB isn't reachable at all. This can have one or more of the following causes:

IP address or hostname in JDBC URL is wrong.
Hostname in JDBC URL is not recognized by local DNS server.
Port number is missing or wrong in JDBC URL.
DB server is down.
DB server doesn't accept TCP/IP connections.
DB server has run out of connections.
Something in between Java and DB is blocking connections, e.g. a firewall or proxy.

RE: Root exception is com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure

Shubham Aware — Thu, 04 Apr 2024 12:29:47 GMT

The error suggests a communication problem between Tomcat and MySQL. Check server status, network, configurations, SSL setup, driver compatibility, database health, and enable detailed logging for diagnosis.