Mods crashing not sure what to do

Note - If you do not fill in every section below, your post won’t be answered - you must provide the steps you have followed so far and the actions you’ve already taken. Make sure to remove this notice from your post too.

Screenshots of text are prohibited. Always copy and paste text as text.

Make sure you search before posting! Duplicate posts for the same issue may not be answered.

OS Name/Version: ubuntu server 24.04.3

Product Name/Version: AMP 2.6.3 - 20250926.1

Problem Description: I tried to add some mods but now it just crashes on startup.

15:27:55
2025-10-20 19:27:55,762 main WARN Advanced terminal features are not available in this environment
main/INFO15:27:55
ModLauncher running: args [--launchTarget, forgeserver, --fml.forgeVersion, 47.4.5, --fml.mcVersion, 1.20.1, --fml.forgeGroup, net.minecraftforge, --fml.mcpVersion, 20230612.114412]
ModLauncher 10.0.9+10.0.9+main.dcd20f30 starting: java version 21.0.8 by Eclipse Adoptium; OS Linux arch amd64 version 6.8.0-85-generic
15:27:56
ImmediateWindowProvider not loading because launch target is forgeserver
SpongePowered MIXIN Subsystem Version=0.8.5 Source=union:/home/amp/.ampdata/instances/ThugShakerCentral01/Minecraft/libraries/org/spongepowered/mixin/0.8.5/mixin-0.8.5.jar%2365!/ Service=ModLauncher Env=SERVER
main/WARN15:27:57
Mod file /home/amp/.ampdata/instances/ThugShakerCentral01/Minecraft/libraries/net/minecraftforge/fmlcore/1.20.1-47.4.5/fmlcore-1.20.1-47.4.5.jar is missing mods.toml file
Mod file /home/amp/.ampdata/instances/ThugShakerCentral01/Minecraft/libraries/net/minecraftforge/javafmllanguage/1.20.1-47.4.5/javafmllanguage-1.20.1-47.4.5.jar is missing mods.toml file
Mod file /home/amp/.ampdata/instances/ThugShakerCentral01/Minecraft/libraries/net/minecraftforge/lowcodelanguage/1.20.1-47.4.5/lowcodelanguage-1.20.1-47.4.5.jar is missing mods.toml file
Mod file /home/amp/.ampdata/instances/ThugShakerCentral01/Minecraft/libraries/net/minecraftforge/mclanguage/1.20.1-47.4.5/mclanguage-1.20.1-47.4.5.jar is missing mods.toml file
Attempted to select two dependency jars from JarJar which have the same identification: Mod File:  and Mod File: . Using Mod File: 
Attempted to select a dependency jar for JarJar which was passed in as source: curios. Using Mod File: /home/amp/.ampdata/instances/ThugShakerCentral01/Minecraft/mods/curios-forge-5.14.1+1.20.1.jar
Attempted to select a dependency jar for JarJar which was passed in as source: resourcefullib. Using Mod File: /home/amp/.ampdata/instances/ThugShakerCentral01/Minecraft/mods/resourcefullib-forge-1.20.1-2.1.29.jar
main/INFO15:27:57
Found 33 dependencies adding them to mods collection
Console15:27:58
Initializing Polytone Transformers
15:28:00
	- mutantmonsters 8.0.7
	- mutil 6.2.0
	- naturalist 5.0pre3
		\-- midnightlib 1.4.2
	- notreepunching 7.1.0
	- nyfsspiders 2.1.1
	- octolib 0.5.0.1
	- ohthetreesyoullgrow 1.4.2
	- pehkui 3.8.2+1.20.1-forge
	- phantasm 1.0.1
	- playeranimator 1.0.2-rc1+1.20
	- polytone 1.20-3.5.9
	- projectile_damage 3.2.2+1.20.1
	- puzzleslib 8.1.33
		\-- puzzlesaccessapi 20.1.1
	- quark 4.0-462
	- radium 0.12.4+git.26c9d8e
	- railways 1.6.13-alpha+forge-mc1.20.1
	- ramcompat 0.1.4
	- relics 0.8.0.11
	- resourcefulconfig 2.1.3
	- resourcefullib 2.1.29
	- soulsweapons 1.2.4-1.20.1-forge}
	- spartanfire 2.1.0
	- spartanshields 3.1.1
	- spartantoolkit 1.20.1-1.6.1
	- spartantwilight 1.20.1-3.1.1
	- spartanweaponry 3.2.1
	- t_and_t 0.0NONE
	- terrablender 3.0.1.10
	- twilightforest 4.3.2508
	- vminus 3.3.1
	- watut 1.20.1-1.2.3
	- waystones 14.1.17
	- yet_another_config_lib_v3 3.6.6+1.20.1-forge
	- yungsapi 1.20-Forge-4.0.6
	- yungsbridges 1.20-Forge-4.0.3
	- zeta 1.0-30
main/WARN15:28:00
Reference map 'itemselector.refmap.json' for l2itemselector.mixins.json could not be read. If this is a development environment you can ignore this message
Reference map 'cristellib-forge-refmap.json' for cristellib.mixins.json could not be read. If this is a development environment you can ignore this message
main/ERROR15:28:00
Attempted to load class net/minecraft/client/gui/screens/Screen for invalid dist DEDICATED_SERVER
main/WARN15:28:00
Error loading class: net/minecraft/client/gui/screens/Screen (java.lang.RuntimeException: Attempted to load class net/minecraft/client/gui/screens/Screen for invalid dist DEDICATED_SERVER)
@Mixin target net.minecraft.client.gui.screens.Screen was not found relics.mixins.json:ScreenMixin
main/ERROR15:28:01
Attempted to load class net/minecraft/client/renderer/item/ItemProperties for invalid dist DEDICATED_SERVER
main/WARN15:28:01
Error loading class: net/minecraft/client/renderer/item/ItemProperties (java.lang.RuntimeException: Attempted to load class net/minecraft/client/renderer/item/ItemProperties for invalid dist DEDICATED_SERVER)
@Mixin target net.minecraft.client.renderer.item.ItemProperties was not found mixins.vminus.json:items.ItemPropertiesMixin
Error loading class: net/raphimc/immediatelyfast/feature/core/BatchableBufferSource (java.lang.ClassNotFoundException: net.raphimc.immediatelyfast.feature.core.BatchableBufferSource)
Error loading class: dev/tr7zw/skinlayers/render/CustomizableModelPart (java.lang.ClassNotFoundException: dev.tr7zw.skinlayers.render.CustomizableModelPart)
Error loading class: me/jellysquid/mods/sodium/client/render/vertex/buffer/SodiumBufferBuilder (java.lang.ClassNotFoundException: me.jellysquid.mods.sodium.client.render.vertex.buffer.SodiumBufferBuilder)
Error loading class: net/fabricmc/fabric/impl/datagen/FabricDataGenHelper (java.lang.ClassNotFoundException: net.fabricmc.fabric.impl.datagen.FabricDataGenHelper)
Error loading class: net/p3pp3rf1y/sophisticatedbackpacks/network/BackpackOpenMessage (java.lang.ClassNotFoundException: net.p3pp3rf1y.sophisticatedbackpacks.network.BackpackOpenMessage)
Error loading class: yalter/mousetweaks/handlers/GuiContainerHandler (java.lang.ClassNotFoundException: yalter.mousetweaks.handlers.GuiContainerHandler)
Error loading class: yalter/mousetweaks/Main (java.lang.ClassNotFoundException: yalter.mousetweaks.Main)
Force-disabling mixin 'alloc.blockstate.StateMixin' as option 'mixin.alloc.blockstate' (added by mods [ferritecore]) disables it and children
main/INFO15:28:02
[java.lang.ThreadGroup:uncaughtException:698]: 	at MC-BOOTSTRAP/cpw.mods.modlauncher@10.0.9/cpw.mods.modlauncher.LaunchServiceHandler.launch(LaunchServiceHandler.java:71)
[java.lang.ThreadGroup:uncaughtException:698]: 	at MC-BOOTSTRAP/cpw.mods.modlauncher@10.0.9/cpw.mods.modlauncher.Launcher.run(Launcher.java:108)
[java.lang.ThreadGroup:uncaughtException:698]: 	at MC-BOOTSTRAP/cpw.mods.modlauncher@10.0.9/cpw.mods.modlauncher.Launcher.main(Launcher.java:78)
[java.lang.ThreadGroup:uncaughtException:698]: 	at MC-BOOTSTRAP/cpw.mods.modlauncher@10.0.9/cpw.mods.modlauncher.BootstrapLaunchConsumer.accept(BootstrapLaunchConsumer.java:26)
[java.lang.ThreadGroup:uncaughtException:698]: 	at MC-BOOTSTRAP/cpw.mods.modlauncher@10.0.9/cpw.mods.modlauncher.BootstrapLaunchConsumer.accept(BootstrapLaunchConsumer.java:23)
[java.lang.ThreadGroup:uncaughtException:698]: 	at cpw.mods.bootstraplauncher@1.1.2/cpw.mods.bootstraplauncher.BootstrapLauncher.main(BootstrapLauncher.java:141)
[java.lang.Throwable:printStackTrace:660]: Caused by: java.lang.reflect.InvocationTargetException
[java.lang.Throwable:printStackTrace:660]: 	at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:118)
[java.lang.Throwable:printStackTrace:660]: 	at java.base/java.lang.reflect.Method.invoke(Method.java:580)
[java.lang.Throwable:printStackTrace:660]: 	at MC-BOOTSTRAP/fmlloader@1.20.1-47.4.5/net.minecraftforge.fml.loading.targets.CommonLaunchHandler.runTarget(CommonLaunchHandler.java:111)
[java.lang.Throwable:printStackTrace:660]: 	at MC-BOOTSTRAP/fmlloader@1.20.1-47.4.5/net.minecraftforge.fml.loading.targets.CommonLaunchHandler.serverService(CommonLaunchHandler.java:103)
[java.lang.Throwable:printStackTrace:660]: 	at MC-BOOTSTRAP/fmlloader@1.20.1-47.4.5/net.minecraftforge.fml.loading.targets.CommonServerLaunchHandler.lambda$makeService$0(CommonServerLaunchHandler.java:27)
[java.lang.Throwable:printStackTrace:660]: 	at MC-BOOTSTRAP/cpw.mods.modlauncher@10.0.9/cpw.mods.modlauncher.LaunchServiceHandlerDecorator.launch(LaunchServiceHandlerDecorator.java:30)
[java.lang.Throwable:printStackTrace:660]: 	... 7 more
[java.lang.Throwable:printStackTrace:673]: Caused by: java.lang.ExceptionInInitializerError
[java.lang.Throwable:printStackTrace:673]: 	at TRANSFORMER/minecraft@1.20.1/net.minecraft.network.chat.MutableComponent.m_237204_(MutableComponent.java:29)
[java.lang.Throwable:printStackTrace:673]: 	at TRANSFORMER/minecraft@1.20.1/net.minecraft.network.chat.Component.m_237115_(Component.java:444)
[java.lang.Throwable:printStackTrace:673]: 	at TRANSFORMER/minecraft@1.20.1/net.minecraft.commands.BrigadierExceptions.<clinit>(BrigadierExceptions.java:24)
[java.lang.Throwable:printStackTrace:673]: 	at TRANSFORMER/minecraft@1.20.1/net.minecraft.SharedConstants.<clinit>(SharedConstants.java:216)
[java.lang.Throwable:printStackTrace:673]: 	at TRANSFORMER/minecraft@1.20.1/net.minecraft.server.Main.main(Main.java:69)
[java.lang.Throwable:printStackTrace:673]: 	at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103)
[java.lang.Throwable:printStackTrace:673]: 	... 12 more
[java.lang.Throwable:lockedPrintStackTrace:696]: Caused by: java.lang.RuntimeException: Attempted to load class net/minecraft/client/gui/screens/Screen for invalid dist DEDICATED_SERVER
[java.lang.Throwable:lockedPrintStackTrace:696]: 	at MC-BOOTSTRAP/fmlloader@1.20.1-47.4.5/net.minecraftforge.fml.loading.RuntimeDistCleaner.processClassWithFlags(RuntimeDistCleaner.java:57)
[java.lang.Throwable:lockedPrintStackTrace:696]: 	at MC-BOOTSTRAP/cpw.mods.modlauncher@10.0.9/cpw.mods.modlauncher.LaunchPluginHandler.offerClassNodeToPlugins(LaunchPluginHandler.java:88)
[java.lang.Throwable:lockedPrintStackTrace:696]: 	at MC-BOOTSTRAP/cpw.mods.modlauncher@10.0.9/cpw.mods.modlauncher.ClassTransformer.transform(ClassTransformer.java:120)
[java.lang.Throwable:lockedPrintStackTrace:696]: 	at MC-BOOTSTRAP/cpw.mods.modlauncher@10.0.9/cpw.mods.modlauncher.TransformingClassLoader.maybeTransformClassBytes(TransformingClassLoader.java:50)
[java.lang.Throwable:lockedPrintStackTrace:696]: 	at cpw.mods.securejarhandler/cpw.mods.cl.ModuleClassLoader.readerToClass(ModuleClassLoader.java:113)
[java.lang.Throwable:lockedPrintStackTrace:696]: 	at cpw.mods.securejarhandler/cpw.mods.cl.ModuleClassLoader.lambda$findClass$15(ModuleClassLoader.java:219)
[java.lang.Throwable:lockedPrintStackTrace:696]: 	at cpw.mods.securejarhandler/cpw.mods.cl.ModuleClassLoader.loadFromModule(ModuleClassLoader.java:229)
[java.lang.Throwable:lockedPrintStackTrace:696]: 	at cpw.mods.securejarhandler/cpw.mods.cl.ModuleClassLoader.findClass(ModuleClassLoader.java:219)
[java.lang.Throwable:lockedPrintStackTrace:696]: 	at cpw.mods.securejarhandler/cpw.mods.cl.ModuleClassLoader.loadClass(ModuleClassLoader.java:135)
[java.lang.Throwable:lockedPrintStackTrace:696]: 	at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:526)
[java.lang.Throwable:lockedPrintStackTrace:696]: 	at TRANSFORMER/minecraft@1.20.1/net.minecraft.resources.ResourceLocation.handler$bcc000$etf$illegalPathOverride(ResourceLocation.java:525)
[java.lang.Throwable:lockedPrintStackTrace:696]: 	at TRANSFORMER/minecraft@1.20.1/net.minecraft.resources.ResourceLocation.m_135841_(ResourceLocation.java:206)
[java.lang.Throwable:lockedPrintStackTrace:696]: 	at TRANSFORMER/minecraft@1.20.1/net.minecraft.resources.ResourceLocation.m_245185_(ResourceLocation.java:241)
[java.lang.Throwable:lockedPrintStackTrace:696]: 	at TRANSFORMER/minecraft@1.20.1/net.minecraft.resources.ResourceLocation.<init>(ResourceLocation.java:40)
[java.lang.Throwable:lockedPrintStackTrace:696]: 	at TRANSFORMER/minecraft@1.20.1/net.minecraft.network.chat.Style.<clinit>(Style.java:39)
[java.lang.Throwable:lockedPrintStackTrace:696]: 	... 18 more
Console15:28:02
Exception in thread "main" 

Steps to reproduce:

  • Step 1: removed all fabric mods and replaced fabric with forge
  • Step 2: added all forge mods, deleted all client side mods
  • Step 3: tried to start server but didnt work and got errors

Actions taken to resolve so far:

Copied console a bunch of times and asked chatgpt what mods to delete but that never worked.

That mixin error there says that some mod is trying to load client-only classes.
You may want to try removing the mods a few at a time until you find the mods that cause the issue.

This topic was automatically closed 30 days after the last reply. New replies are no longer allowed.