java.lang.UnsupportedClassVersionError: Unsupported major.minor version 51.0

Question

When i try to compile my GWT application i'm getting below exception. Any idea ? Thanks in advance.

Loading inherited module 'widgets.PresentationWidgets'
   [ERROR] Unexpected error while processing XML
java.lang.UnsupportedClassVersionError: gwt/widgets/server/datagrid/util/WrapperGenerator : Unsupported major.minor version 51.0
    at java.lang.ClassLoader.defineClass1(Native Method)
    at java.lang.ClassLoader.defineClassCond(ClassLoader.java:632)
    at java.lang.ClassLoader.defineClass(ClassLoader.java:616)
    at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:141)
    at java.net.URLClassLoader.defineClass(URLClassLoader.java:283)
    at java.net.URLClassLoader.access$000(URLClassLoader.java:58)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:197)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)

You are trying to run a jar compiled with JDK 1.7 on a 1.6 or less JVM — fge, Feb 18 '14 at 09:57
May be you are using jars compiled with lower version of yours. Check the jar class java version. — Rahul, Feb 18 '14 at 09:57
You will find your answer hre: http://stackoverflow.com/questions/10382929/unsupported-major-minor-version-51-0 Possibly this question is a duplicate. [1]: — dstronczak, Feb 18 '14 at 09:59
Im getting this error when i trying to compile the GWT application. Not when running the application. — Dilantha, Feb 18 '14 at 10:03
Right, your GWT compiler is running with JDK 1.6, but one of the jars on your classpath was compiled (at least in part) with JDK 1.7. — Colin Alworth, Feb 18 '14 at 19:44

score 2 · Accepted Answer · edited May 23 '17 at 12:14

clearly, your Java runtime evnironment is different from that of compile time version

For me this solved the problem: I have a 64-bit system with jdk1.7 (32bit) and jdk1.6 (64 bit) installed. Even though I had specified PATH and JAVA_HOME for jdk1.7, my java -version was 1.6

I removed the folder in which jdk1.6 was installed

. The problem was gone. Apparently, a 64 bit system gave preference to jdk1.6(64bit) instead of jdk1.7(32bit)

For more info, refer: How to fix java.lang.UnsupportedClassVersionError: Unsupported major.minor version

java.lang.UnsupportedClassVersionError: Unsupported major.minor version 51.0

1 Answers1