Error with Tomcat 6 and Tomcat 5.5 Incompatibility

Question

I developed a Tomcat application using Tomcat 6 for testing. I have now deployed it to Tomcat 5.5 - when I invoke the servlet I get an error which doesn't make much sense to me. Does anyone know what causes this error.

exception

javax.servlet.ServletException: Error allocating a servlet instance org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:117) org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:174) org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:874) org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.processConnection(Http11BaseProtocol.java:665) org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:528) org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:81) org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:689) java.lang.Thread.run(Thread.java:595) root cause

java.lang.UnsupportedClassVersionError: Bad version number in .class file java.lang.ClassLoader.defineClass1(Native Method) java.lang.ClassLoader.defineClass(ClassLoader.java:620) java.security.SecureClassLoader.defineClass(SecureClassLoader.java:124) org.apache.catalina.loader.WebappClassLoader.findClassInternal(WebappClassLoader.java:1853) org.apache.catalina.loader.WebappClassLoader.findClass(WebappClassLoader.java:875) org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1330) org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1209) java.security.AccessController.doPrivileged(Native Method) org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:117) org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:174) org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:874) org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.processConnection(Http11BaseProtocol.java:665) org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:528) org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:81) org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:689) java.lang.Thread.run(Thread.java:595)

Answer 1

This has nothing to do with tomcat. The error is caused by .class file version difference.

Most likely, you've compiled a .class file with Java6, and have tried to run it on Java5.

The solution is to either run tomcat5.5 on the newer version of Java, or just recompile.