Made a ticket before, admin closed while probably not reading and seeing that the issue was not related to the fact that I used 1.12.2. This is on the stable 1.16.5 server.

>java -Xmx1G -Xms1G -jar forge-1.16.5-36.1.0.jar
2021-06-21 18:28:28,771 main WARN Advanced terminal features are not available in this environment
[18:28:28] [main/INFO] [cp.mo.mo.Launcher/MODLAUNCHER]: ModLauncher running: args [--gameDir, ., --launchTarget, fmlserver, --fml.forgeVersion, 36.1.0, --fml.mcpVersion, 20210115.111550, --fml.mcVersion, 1.16.5, --fml.forgeGroup, net.minecraftforge]
[18:28:28] [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 @0x29f69090) cannot access class sun.security.util.ManifestEntryVerifier (in module java.base) because module java.base does not export sun.security.util to unnamed module @0x29f69090
        at cpw.mods.modlauncher.SecureJarHandler.lambda$static$1(SecureJarHandler.java:41)
        at cpw.mods.modlauncher.api.LamdbaExceptionUtils.uncheck(LamdbaExceptionUtils.java:95)
        at cpw.mods.modlauncher.SecureJarHandler.<clinit>(SecureJarHandler.java:41)
        at cpw.mods.modlauncher.Launcher.lambda$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:63)
        at net.minecraftforge.server.ServerMain$Runner.access$100(ServerMain.java:60)
        at net.minecraftforge.server.ServerMain.main(ServerMain.java:57)

 

Edited June 21, 20214 yr by MyAngelAku

Which Java version is the latest one supported by 1.12.2 servers then? Or rather, where can I find out if you for some reason don't want to give out any info on 1.12.2 servers?

Edited June 21, 20214 yr by MyAngelAku

1.12 is no longer supported on this forum.

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

Also, common sense/and actually putting in effort by using the search feature  of this site would answer your questions.
That is the reason we lock old threads, because the questions have been answered a thousand times before during the supported lifecycle of that version.