This is the error you will see when you try to load a class file into a JVM that is older than the version of javac used to compile it. For example, if you compile your class with the javac program that came with jdk1.6 but are running your container with the JVM that came with jdk1.5 you will see this error.
To fix, you can either re-compile your class with the same version that you are using to run your container, upgrade the version of Java that you are using to run your container, or use the "-source" switch when compiling to let the JVM know that this class (even though compiled with a newer compiler) doesn't contain any features that are not compatible with the version under which you are trying to run it.
Joined: Mar 13, 2007
Thank you, that was the mistake. I used version 6 to compile it, but in Apache Tomcat there was version 5. I changed the version in Apache Tomcat to 6, now it works.