KB-2178 Tomcat startup fails with "java.sql.SQLException: Unable to load class: org.mysql.jdbc.Driver" exception

Symptoms

When starting Tomcat via start-appserver.sh or start-appserver.bat, the startup fails with the following message observed in the application server log:

SEVERE [localhost-startStop-1] org.apache.tomcat.jdbc.pool.ConnectionPool.init Unable to create initial connections of pool.
 java.sql.SQLException: Unable to load class: org.mysql.jdbc.Driver from ClassLoader:java.net.URLClassLoader@31221be2;ClassLoader:AppianWebappClassLoader
 context: suite
 delegate: false
----------> Parent Classloader:
java.net.URLClassLoader@31221be2

Cause

The classname for the MySQL driver has incorrectly been prefaced with org rather than com.

Action

Correct the driverClassName found in tomcatResources.xml file located in <APPIAN_HOME>/conf and restart Tomcat. The accurate convention is: driverClassName="com.mysql.jdbc.Driver"

Affected Versions

This article applies to Appian 18.3 and later.

Last Reviewed: April 2021