Unsupported major.minor version 49.0

Question

I am getting the following exception whenever I login to my application ...

javax.servlet.ServletException: com/sun/org/apache/xalan/internal/xsltc/

Answer 1

You have a mismatch between your JVM that you're using to run the .class, and the version of Java used to compile the .class. The JVM running it is an earlier version of the JVM used to compile that class.

As detailed here, you have a version 1.5 class that you're trying to run on an earlier JVM.

EDIT : WAS 5.1 uses JDK 1.4, it would appear.