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Trouble Starting Forge Server for Minecraft 1.20.1

Posted May 2, 20241 yr

Hello,

I am trying to start my forge-modded server. I go to the point of invoking the run.bat, but I get the following error:

java.lang.IllegalArgumentException: Unsupported class file major version 66

I have Java SE Dev Kit 22.0.1 installed. Do I need to downgrade?

Before starting a Forge dedicated server, I created a vanilla server. I did get an error when trying to connect, but I figured it was because I had mods running on the client.

Sadly, I am pretty much "unconscious incompetent" here.

Thanks for any advice.

Edited May 4, 20241 yr by Redempsyn
Stated wrong Java version installed and added details

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May 2, 20241 yr

Hello there, you have the wrong Java version and you need to update not downgrade. I hope this helps

Quote

May 2, 20241 yr

Minecraft 1.20.1 requires Java 17 to work

Try my Modpack

>>Link to Curseforge<<

Quote

May 3, 20241 yr

Author

Hi Guys,

Thanks for the replies. From what I can see I have the latest version of Java. I have Java 8 update 411 and Java SE Development Kit 22.0.1. It was late for me and I meant 22.0.1 not 11.0.1. Should I only have one installed?

Thanks again!

Edited May 3, 20241 yr by Redempsyn
Clarity

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May 3, 20241 yr

Try and uninstall both and get Java 17

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May 3, 20241 yr

You can have multiple Java version installed

For the server, you have to set the path to java 17 in your startscript

For example:

"C:\Program Files\Java\jdk-17.0.9\bin\javaw.exe" -Xmx4G -Xms2048M -jar forgeserver.jar 
pause

Just make sure the path is correct and keep the quotation marks

And the forgeserver jar name should match

Try my Modpack

>>Link to Curseforge<<

Quote

May 5, 20241 yr

Author

Hi Guys,

Thanks again for the replies. Uninstalling version 22 fixed my issue. I tried starting the server using the suggestion @TileEntity gave but could not see how to invoke Forge. I then uninstalled JDK version 22 as @Xoroshio advised. I may have to stay with having only JDK 17 installed. Now I need to figure out why the startup does not like the number of mods I installed.

Quote

May 6, 20241 yr

you probably need to give it more RAM

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Hey dawg!

I think I might be able to help you out with your issue here. I say might because I don't know about 1.16.x or any later version, but I know how to do this kind of thing for 1.12.2 forge. Basically, in the pre-init or init (I don't really remember which one) you just gotta'

Okay, ykw, I just downloaded the 1.14.4 1.20.1 minecraft mdk. I think I actually can help you here. So, the 1.12.2 method actually doesn't work with 1.20.1 minecraft or later. Probably not too far before either. I see two options here for ya':

First, it's important to note that the game stores its spawn data for structures in, well, the Structures class. Here, the game initializes an instance of each Structure class and registers them with the BootstrapContext using its bootstrap function. Each instance of a Structure class is registered with a StructureSettings class as an argument. One of the arguments, the one that you're probably going to be particularly interested in here, would be the spawnOverrides argument. For this argument, the game uses a Map between MOB_CATEGORIES and StructureSpawnOverride. StructureSpawnOverride is essentially the juice of it here. It contains almost everything you would need to control how your custom mob spawns in Pillager Outposts. Now, if you want to change how the Structure class for the pillager outposts is registered with the BootstrapContext in the bootstrap function, you're going to want to change where the function's caller gets the function and replace it with your own custom version of this function. How might you do this? This is where it gets a little tricky. The bootstrap function for the structures class is referenced in VanillaRegistries.BUILDER. However, unfortunately, this field is private and final, so you can't directly change it with reflections, but you can still access it with reflections. Now the VanillaRegistries.BUILDER field is of the type RegistrySetBuilder, which uses a private final field "entires", which is set as a List<RegistrySetBuilder.RegistryStub<?>> type. So here, you could use reflections to access this list field and remove the entry for the structures bootstrap. Then you might be able to create your own structures class and add change the bootstrap function to reflect the changes you wish. Then finally, simply re-add the Structure entry that you made to the list, and you should be completely done! Keep in mind, I haven't actually tested this, so I'm not sure if it would actually work, and even if it did work it's really unorthodox, so I would recommend trying this next idea.

When the game is deciding whether or not to spawn an entity, if the entity is registered with the SpawnPlacements class, is uses the function you specify in the entity class to determine whether or not the entity can spawn in a certain spot. For example, the guardian cannot spawn on a block that is exposed to light from underwater because of this function. So what you could do is make a checkSelfSpawnRules function for your mob and register it with the SpawnPlacements function. Then, you could have your checkSelfSpawnRules function take into account if the block it's trying to spawn on is near a Pillager Outpost. Finally, you can get the coordinates to the chunk of your block and iterate through the ServerLevels in your MinecraftServer class and get their chunk sources and test if the chunk source has the chunk of your block position. If it does, you can then get the StructureManager from the ServerLevel. In there should be some very helpful functions for you to use. Although this is a bit more orthodox, it might be a bit laggy.

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mechamanns

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Trouble Starting Forge Server for Minecraft 1.20.1

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