AndyM2009

Well, I have no clue then. It would not run without that being installed.

It does on the MAC - because it wants to find it in the JAVA HOME path!!! It runs now!

Yep - turns out the "big red button" on the Oracle site is just updating the JRE and that is fine for Minecraft. Forge needs the JDK to be downloaded.....

I had found it just before you posted. Trouble is the commands to uninstall Java are not touching that (and it is Java 16 as predicted). On MAC OS

I know that is what it says, but even if I uninstall Java it says the same. The Java control portal also says Java 8 is the only version present.

Very true, and that is the only version of Java installed on the system.

I have downloaded and installed the forge server 1.16.5. In the installation folder the vanilla Minecraft server runs perfectly. In the same folder the forge server says it is trying to launch Java version 16. Java 8 is the only version installed. Curiously, the error message is exactly the same if I uninstall Java entirely. Essentially, this happens (along with a stack trace): [16:48:12] [main/INFO] [cp.mo.mo.Launcher/MODLAUNCHER]: ModLauncher running: args [--gameDir, ., --launchTarget, fmlserver, --fml.forgeVersion, 36.2.20, --fml.mcpVersion, 20210115.111550, --fml.mcVersion, 1.16.5, --fml.forgeGroup, net.minecraftforge] [16:48:12] [main/INFO] [cp.mo.mo.Launcher/MODLAUNCHER]: ModLauncher 8.0.9+86+master.3cf110c starting: java version 16.0.1 by Oracle Corporation Exception in thread "main" java.lang.IllegalAccessError: class cpw.mods.modlauncher.SecureJarHandler (in unnamed module @0x40f9161a) cannot access class sun.security.util.ManifestEntryVerifier (in module java.base) because module java.base does not export sun.security.util to unnamed module @0x40f9161a Any ideas? Andy