Unable to run jetty start.jar

Question

When I run start.jar I get the following error:

 Exception in thread "main" java.lang.UnsupportedClassVersionError: org/eclipse/
 jetty/start/Main : Unsupported major.minor version 51.0
    at java.lang.ClassLoader.defineClass1(Native Method)
    at java.lang.ClassLoader.defineClassCond(Unknown Source)
    at java.lang.ClassLoader.defineClass(Unknown Source)
    at java.security.SecureClassLoader.defineClass(Unknown Source)
    at java.net.URLClassLoader.defineClass(Unknown Source)
    at java.net.URLClassLoader.access$000(Unknown Source)
    at java.net.URLClassLoader$1.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(Unknown Source)
    at java.lang.ClassLoader.loadClass(Unknown Source)
    at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
    at java.lang.ClassLoader.loadClass(Unknown Source)
 Could not find the main class: org.eclipse.jetty.start.Main. Program will exit.

According to the Jetty documentation (http://www.eclipse.org/jetty/documentation/current/quickstart-running-jetty.html), all I need to do is download the zip, extract, and run start.jar. Google doesn't seem to provide me with any people having similar issues.

Thanks, Sam

Answer 1

Take a look on the following discussion and specifically on the most popular answer.

Shortly you have a problem of class version incompatibility. Your jetty is compiled with compiler of java 7 while you are trying to run it with JVM of previous version. The solution is: go forward to Java 7: upgrade your JDK and configure eclipse to use java 7 and start enjoying the new features.