java.lang.UnsupportedClassVersionError: Bad version number in .class fileit means that the Java ClassLoader cannot load a certain class because it has been compiled using a different version of the JDK. For example, you might see this error if your application has been compiled using Java 1.5, but an external library you are calling has been compiled using 1.6. You can use the
javapcommand to find out what the version number of a class file is:
sharfah@starship:~> javap -v MyApp | grep version minor version: 0 major version: 5050 refers to Java 1.6, while 49 refers to Java 1.5.