Nightnova

That did the trick.

I had my head so wrapped around getting Java installed properly, I thought it might have something to do with it and completely missed checking the HD version.

Thanks and glad it's working now!  

Hero Games store at the end of 2020. I just got around to installing Java as my computer took a dive and I was in between systems for a while. Has there been an update to HD since then?

Greetings.

I'm on a Windows 10 Home machine (64-bit). I went to java(dot)com and downloaded the most recent version of Java SE version 8. After installing it, I followed a tutorial to properly path it. When I attempted to run HERO Designer, I received a JNI error message. I proceeded to try and run it from the command line and received the following information:

E:\HERO Designer>java -jar HD6.jar
Error: A JNI error has occurred, please check your installation and try again
Exception in thread "main" java.lang.UnsupportedClassVersionError: com/hero/Launcher has been compiled by a more recent version of the Java Runtime (class file version 58.0), this version of the Java Runtime only recognizes class file versions up to 52.0
        at java.lang.ClassLoader.defineClass1(Native Method)
        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$100(Unknown Source)
        at java.net.URLClassLoader$1.run(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)
        at sun.launcher.LauncherHelper.checkAndLoadMain(Unknown Source)

E:\HERO Designer>java -version
java version "1.8.0_321"
Java(TM) SE Runtime Environment (build 1.8.0_321-b07)
Java HotSpot(TM) Client VM (build 25.321-b07, mixed mode, sharing)

Seems like a version issue? I'm not sure how to fix it. Please help!