If you are using the Beans Validation framework (JSR 349), you may encounter this obscure exception when doing your validation.
java.lang.ExceptionInInitializerError
Caused by: javax.el.ELException: Provider com.sun.el.ExpressionFactoryImpl not found
Caused by: java.lang.ClassNotFoundException: com.sun.el.ExpressionFactoryImpl
This exception is caused by a missing key lookup in the ValidationMessages.properties file. Make sure you have the the key in the properties file.
Enjoy!
