This happened when you tried to create an entity from a database. I am currently using Wildfly 8.1.0, and MySQL 5.1.30 on NetBeans 8.0. To resolve this issue, open the standalone-full.xml of JBOSS. Under the datasources > drivers > driver, make sure the driver name is the same as the datasource > driver. For example, make sure the text highlighted in the following code block is the same: < subsystem xmlns = "urn:jboss:domain:datasources:2.0" > < datasources > < datasource jta = "false" jndi-name = "java:jboss/mysql" pool-name = "mysql" enabled = "true" use-ccm = "false" > < connection-url > jdbc:mysql://localhost:3306/client </ connection-url > < driver-class > com.mysql.jdbc.Driver </ driver-class > < driver > mysql </ driver > </ datasource > < drivers > < dr