When trying to start the server with the start.bat, this pops up in the console:

java -Xmx6144M -Xms6144M -jar forge-1.16.5-36.2.39.jar nogui
2023-02-03 02:30:06,287 main WARN Advanced terminal features are not available in this environment
[02:30:06] [main/INFO] [cp.mo.mo.Launcher/MODLAUNCHER]: ModLauncher running: args [--gameDir, ., --launchTarget, fmlserver, --fml.forgeVersion, 36.2.39, --fml.mcpVersion, 20210115.111550, --fml.mcVersion, 1.16.5, --fml.forgeGroup, net.minecraftforge, nogui]
[02:30:06] [main/INFO] [cp.mo.mo.Launcher/MODLAUNCHER]: ModLauncher 8.1.3+8.1.3+main-8.1.x.c94d18ec starting: java version 17.0.4.1 by Oracle Corporation
Exception in thread "main" java.lang.IllegalAccessError: class cpw.mods.modlauncher.SecureJarHandler (in unnamed module @0x7ea37dbf) cannot access class sun.security.util.ManifestEntryVerifier (in module java.base) because module java.base does not export sun.security.util to unnamed module @0x7ea37dbf
        at cpw.mods.modlauncher.SecureJarHandler.lambda$static$1(SecureJarHandler.java:45)
        at cpw.mods.modlauncher.api.LamdbaExceptionUtils.uncheck(LamdbaExceptionUtils.java:95)
        at cpw.mods.modlauncher.SecureJarHandler.<clinit>(SecureJarHandler.java:45)
        at cpw.mods.modlauncher.Launcher.lambda$new$6(Launcher.java:55)
        at java.base/java.util.concurrent.ConcurrentHashMap.computeIfAbsent(ConcurrentHashMap.java:1708)
        at cpw.mods.modlauncher.api.TypesafeMap.computeIfAbsent(TypesafeMap.java:52)
        at cpw.mods.modlauncher.api.TypesafeMap.computeIfAbsent(TypesafeMap.java:47)
        at cpw.mods.modlauncher.Environment.computePropertyIfAbsent(Environment.java:62)
        at cpw.mods.modlauncher.Launcher.<init>(Launcher.java:55)
        at cpw.mods.modlauncher.Launcher.main(Launcher.java:66)
        at net.minecraftforge.server.ServerMain$Runner.runLauncher(ServerMain.java:49)
        at net.minecraftforge.server.ServerMain$Runner.access$100(ServerMain.java:46)
        at net.minecraftforge.server.ServerMain.main(ServerMain.java:43)

I am using Java 8.

12 hours ago, Raptorian said:

[02:30:06] [main/INFO] [cp.mo.mo.Launcher/MODLAUNCHER]: ModLauncher 8.1.3+8.1.3+main-8.1.x.c94d18ec starting: java version 17.0.4.1 by Oracle Corporation

Definitely not.

But otherwise:

The version you are using is no longer supported on this forum.

Please update to a modern version of Minecraft to receive support.

Currently supported versions are 1.19.3 (Latest), 1.19.2, and 1.18.2 (LTS).