KB-1023 "Unsupported major.minor version" error thrown when running the configure script

Symptoms

When running the configure script, the following is printed:

Exception in thread "main" java.lang.UnsupportedClassVersionError: com/appian/configure/Menu: Unsupported major.minor version XX.X
        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)

Cause

The UnsupportedClassVersionError is thrown when the JVM tries to load a class and finds that the class file version is not supported. This particular issue occurs when a higher JDK version is used to compile the source file and a lower JDK version is used to run the program.

Action

To correct the issue, perform the following:

1. Check the System Requirements page for the correct supported JDK for your version of Appian.
2. Download and install the minimum required JDK or higher from Java specific to your operating system:
   • Java 7
   • Java 8
3. Update the JAVA_HOME environment variable to point to the JDK installation directory by following the instructions here.
4. Restart the command prompt/terminal session and the issue should be resolved.

Affected Versions

This article applies to Appian 7.9 and later.