java.lang.UnsupportedClassVersionError: org/openqa/gr id/selenium/GridLauncher (Unsupported major.minor version 50.0)

That message (with version 50.0) indicates that Selenium server requires java 6 to run, but you're trying to run it with some earlier version of java.

To find out what version of java you're using, run:

java -version

If you have java 6 installed, but it isn't getting used, you may have to give the full path name to the java executable, so something like this if on linux:

/usr/local/jre6/bin/java -jar selenium.jar

or like this if on windows:

"C:\Program Files (x86)\Java\jre6\bin\java.exe" -jar selenium.jar

(Of course, you'll need to adjust that command to match where java actually lives on your machine)

I had the same problem, I was using jre6, I went to the project properties, changed the JRE system library to use jre1.8 and it worked.. you can select alternate jre and add the latest jre installed on your system.

Besides the Java version, the Java vendor can apparently be another important variable. I landed on this thread with a variation of the OP's problem where the stack trace indicated that Java 8 was required, even though I was already using OpenJDK 8.

Exception in thread "main" java.lang.UnsupportedClassVersionError: org/openqa/grid/selenium/GridLauncherV3 : Unsupported major.minor version 52.0 at java.lang.ClassLoader.defineClass1(Native Method) at java.lang.ClassLoader.defineClass(ClassLoader.java:800) at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142) at java.net.URLClassLoader.defineClass(URLClassLoader.java:449) at java.net.URLClassLoader.access$100(URLClassLoader.java:71) at java.net.URLClassLoader$1.run(URLClassLoader.java:361) at java.net.URLClassLoader$1.run(URLClassLoader.java:355) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(URLClassLoader.java:354) at java.lang.ClassLoader.loadClass(ClassLoader.java:425) at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308) at java.lang.ClassLoader.loadClass(ClassLoader.java:358) at sun.launcher.LauncherHelper.checkAndLoadMain(LauncherHelper.java:482)

Switching to Oracle's JVM got me past this.