GUI Buttons don't work

Status
Can not reproduce
Issue description

I know there are already reports such as this one, but none of those helped me. When I click on the button, in my multiplayer server console it says:

[22:32:37] [Server thread/FATAL] [minecraft/MinecraftServer]: Error executing task

java.util.concurrent.ExecutionException: java.lang.NoSuchMethodError: net.minecraft.network.play.client.CPacketCloseWindow.<init>(I)V

at java.util.concurrent.FutureTask.report(FutureTask.java:122) ~[?:1.8.0_212]

at java.util.concurrent.FutureTask.get(FutureTask.java:192) ~[?:1.8.0_212]

at net.minecraft.util.Util.func_181617_a(SourceFile:47) [h.class:?]

at net.minecraft.server.MinecraftServer.func_71190_q(MinecraftServer.java:842) [MinecraftServer.class:?]

at net.minecraft.server.dedicated.DedicatedServer.func_71190_q(DedicatedServer.java:464) [nz.class:?]

at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:786) [MinecraftServer.class:?]

at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:667) [MinecraftServer.class:?]

at java.lang.Thread.run(Thread.java:748) [?:1.8.0_212]

Caused by: java.lang.NoSuchMethodError: net.minecraft.network.play.client.CPacketCloseWindow.<init>(I)V

at org.bukkit.craftbukkit.v1_12_R1.event.CraftEventFactory.callInventoryOpenEvent(CraftEventFactory.java:790) ~[CraftEventFactory.class:git-HEAD-a8543ec]

at net.minecraftforge.fml.common.network.internal.FMLNetworkHandler.openGui(FMLNetworkHandler.java:107) ~[FMLNetworkHandler.class:git-HEAD-a8543ec]

at net.minecraft.entity.player.EntityPlayer.openGui(EntityPlayer.java:2732) ~[aed.class:?]

at net.mcreator.eas.MCreatorEasthunderstormCommandExecuted.executeProcedure(MCreatorEasthunderstormCommandExecuted.java:42) ~[MCreatorEasthunderstormCommandExecuted.class:?]

at net.mcreator.eas.MCreatorEASGUI$GUIButtonPressedMessageHandler.lambda$onMessage$0(MCreatorEASGUI.java:197) ~[MCreatorEASGUI$GUIButtonPressedMessageHandler.class:?]

at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) ~[?:1.8.0_212]

at java.util.concurrent.FutureTask.run(FutureTask.java:266) ~[?:1.8.0_212]

at net.minecraft.util.Util.func_181617_a(SourceFile:46) ~[h.class:?]

... 5 more

Issue comments

Another thing I forgot to add. My server is running forge and bukkit (and for the other people who don't believe this, it is true.) and the forge version is 2812. I tried changing that to a higher version but it makes the server stop working.

MCreator only supports Minecraft Forge 2768. Other versions might crash, especially if combined with other APIs such as bukkit. GUIs work on Forge only servers (I tried to replicate your bug) so I can't say what is causing this.

Will there be any support for later forge versions with other APIs in the future?