Warning coremod present

How on earth do I fix this?

---- Minecraft Crash Report ----

WARNING: coremods are present:
llibrary (llibrary-core-1.0.11-1.12.2.jar)
midnight (themidnight-0.3.5.jar)
Quark Plugin (Quark-r1.6-179.jar)
Contact their authors BEFORE contacting forge

// Hey, Don’t be sad. Have a hug <3

Time: 9/7/20 11:15 PM
Description: Initializing game

java.lang.NoClassDefFoundError: cpw/mods/fml/common/network/IGuiHandler
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:348)
at net.minecraftforge.fml.common.FMLModContainer.constructMod(FMLModContainer.java:539)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at com.google.common.eventbus.Subscriber.invokeSubscriberMethod(Subscriber.java:91)
at com.google.common.eventbus.Subscriber$SynchronizedSubscriber.invokeSubscriberMethod(Subscriber.java:150)
at com.google.common.eventbus.Subscriber$1.run(Subscriber.java:76)
at com.google.common.util.concurrent.MoreExecutors$DirectExecutor.execute(MoreExecutors.java:399)
at com.google.common.eventbus.Subscriber.dispatchEvent(Subscriber.java:71)
at com.google.common.eventbus.Dispatcher$PerThreadQueuedDispatcher.dispatch(Dispatcher.java:116)
at com.google.common.eventbus.EventBus.post(EventBus.java:217)
at net.minecraftforge.fml.common.LoadController.sendEventToModContainer(LoadController.java:219)
at net.minecraftforge.fml.common.LoadController.propogateStateMessage(LoadController.java:197)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at com.google.common.eventbus.Subscriber.invokeSubscriberMethod(Subscriber.java:91)
at com.google.common.eventbus.Subscriber$SynchronizedSubscriber.invokeSubscriberMethod(Subscriber.java:150)
at com.google.common.eventbus.Subscriber$1.run(Subscriber.java:76)
at com.google.common.util.concurrent.MoreExecutors$DirectExecutor.execute(MoreExecutors.java:399)
at com.google.common.eventbus.Subscriber.dispatchEvent(Subscriber.java:71)
at com.google.common.eventbus.Dispatcher$PerThreadQueuedDispatcher.dispatch(Dispatcher.java:116)
at com.google.common.eventbus.EventBus.post(EventBus.java:217)
at net.minecraftforge.fml.common.LoadController.distributeStateMessage(LoadController.java:136)
at net.minecraftforge.fml.common.Loader.loadMods(Loader.java:593)
at net.minecraftforge.fml.client.FMLClientHandler.beginMinecraftLoading(FMLClientHandler.java:232)
at net.minecraft.client.Minecraft.func_71384_a(Minecraft.java:467)
at net.minecraft.client.Minecraft.func_99999_d(Minecraft.java:378)
at net.minecraft.client.main.Main.main(SourceFile:123)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at net.minecraft.launchwrapper.Launch.launch(Launch.java:135)
at net.minecraft.launchwrapper.Launch.main(Launch.java:28)
Caused by: java.lang.ClassNotFoundException: cpw.mods.fml.common.network.IGuiHandler
at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:191)
at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
… 39 more
Caused by: java.lang.NullPointerException
at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:182)
… 41 more

A detailed walkthrough of the error, its code path and all known details is as follows:

– Head –
Thread: Client thread
Stacktrace:
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:348)
at net.minecraftforge.fml.common.FMLModContainer.constructMod(FMLModContainer.java:539)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at com.google.common.eventbus.Subscriber.invokeSubscriberMethod(Subscriber.java:91)
at com.google.common.eventbus.Subscriber$SynchronizedSubscriber.invokeSubscriberMethod(Subscriber.java:150)
at com.google.common.eventbus.Subscriber$1.run(Subscriber.java:76)
at com.google.common.util.concurrent.MoreExecutors$DirectExecutor.execute(MoreExecutors.java:399)
at com.google.common.eventbus.Subscriber.dispatchEvent(Subscriber.java:71)
at com.google.common.eventbus.Dispatcher$PerThreadQueuedDispatcher.dispatch(Dispatcher.java:116)
at com.google.common.eventbus.EventBus.post(EventBus.java:217)
at net.minecraftforge.fml.common.LoadController.sendEventToModContainer(LoadController.java:219)
at net.minecraftforge.fml.common.LoadController.propogateStateMessage(LoadController.java:197)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at com.google.common.eventbus.Subscriber.invokeSubscriberMethod(Subscriber.java:91)
at com.google.common.eventbus.Subscriber$SynchronizedSubscriber.invokeSubscriberMethod(Subscriber.java:150)
at com.google.common.eventbus.Subscriber$1.run(Subscriber.java:76)
at com.google.common.util.concurrent.MoreExecutors$DirectExecutor.execute(MoreExecutors.java:399)
at com.google.common.eventbus.Subscriber.dispatchEvent(Subscriber.java:71)
at com.google.common.eventbus.Dispatcher$PerThreadQueuedDispatcher.dispatch(Dispatcher.java:116)
at com.google.common.eventbus.EventBus.post(EventBus.java:217)
at net.minecraftforge.fml.common.LoadController.distributeStateMessage(LoadController.java:136)
at net.minecraftforge.fml.common.Loader.loadMods(Loader.java:593)
at net.minecraftforge.fml.client.FMLClientHandler.beginMinecraftLoading(FMLClientHandler.java:232)
at net.minecraft.client.Minecraft.func_71384_a(Minecraft.java:467)

– Initialization –
Details:
Stacktrace:
at net.minecraft.client.Minecraft.func_99999_d(Minecraft.java:378)
at net.minecraft.client.main.Main.main(SourceFile:123)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:497)
at net.minecraft.launchwrapper.Launch.launch(Launch.java:135)
at net.minecraft.launchwrapper.Launch.main(Launch.java:28)

– System Details –
Details:
Minecraft Version: 1.12.2
Operating System: Windows 10 (amd64) version 10.0
Java Version: 1.8.0_51, Oracle Corporation
Java VM Version: Java HotSpot™ 64-Bit Server VM (mixed mode), Oracle Corporation
Memory: 266605784 bytes (254 MB) / 671088640 bytes (640 MB) up to 2147483648 bytes (2048 MB)
JVM Flags: 8 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx2G -XX:+UnlockExperimentalVMOptions -XX:+UseG1GC -XX:G1NewSizePercent=20 -XX:G1ReservePercent=20 -XX:MaxGCPauseMillis=50 -XX:G1HeapRegionSize=32M
IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
FML: MCP 9.42 Powered by Forge 14.23.5.2838 24 mods loaded, 24 mods active
States: ‘U’ = Unloaded ‘L’ = Loaded ‘C’ = Constructed ‘H’ = Pre-initialized ‘I’ = Initialized ‘J’ = Post-initialized ‘A’ = Available ‘D’ = Disabled ‘E’ = Errored

| State | ID                   | Version           | Source                                               | Signature                                |
|:----- |:-------------------- |:----------------- |:---------------------------------------------------- |:---------------------------------------- |
| LC    | minecraft            | 1.12.2            | minecraft.jar                                        | None                                     |
| LC    | mcp                  | 9.42              | minecraft.jar                                        | None                                     |
| LC    | FML                  | 8.0.99.99         | forge-1.12.2-14.23.5.2838.jar                        | e3c3d50c7c986df74c645c0ac54639741c90a557 |
| LC    | forge                | 14.23.5.2838      | forge-1.12.2-14.23.5.2838.jar                        | e3c3d50c7c986df74c645c0ac54639741c90a557 |
| LC    | quark                | r1.6-179          | Quark-r1.6-179.jar                                   | None                                     |
| LC    | autoreglib           | 1.3-32            | AutoRegLib-1.3-32.jar                                | None                                     |
| LC    | biomesoplenty        | 7.0.1.2444        | BiomesOPlenty-1.12.2-7.0.1.2444-universal.jar        | None                                     |
| LC    | chesttransporter     | 2.8.8             | ChestTransporter-1.12.2-2.8.8 - Copy.jar             | None                                     |
| LC    | clumps               | 3.1.2             | Clumps-3.1.2 - Copy.jar                              | None                                     |
| LC    | cucumber             | 1.1.3             | Cucumber-1.12.2-1.1.3 - Copy.jar                     | None                                     |
| L     | ironchest            | 1.12.2-7.0.67.844 | ironchest-1.12.2-7.0.72.847 - Copy.jar               | None                                     |
| L     | lunatriuscore        | 1.2.0.42          | LunatriusCore-1.12.2-1.2.0.42-universal.jar          | None                                     |
| L     | llibrary             | 1.7.19            | llibrary-1.7.19-1.12.2 (2).jar                       | None                                     |
| L     | mowziesmobs          | 1.5.8             | mowziesmobs-1.5.8 - Copy.jar                         | None                                     |
| L     | mysticalagriculture  | 1.7.5             | MysticalAgriculture-1.12.2-1.7.5 (1).jar             | None                                     |
| L     | mysticalagradditions | 1.3.2             | MysticalAgradditions-1.12.2-1.3.2.jar                | None                                     |
| L     | harvestcraft         | 1.12.2zb          | Pam's+HarvestCraft+1.12.2zg - Copy.jar               | None                                     |
| L     | patchouli            | 1.0-21            | Patchouli-1.0-21 - Copy.jar                          | None                                     |
| L     | schematica           | 1.8.0.169         | Schematica-1.12.2-1.8.0.169-universal - Copy.jar     | None                                     |
| L     | tragicmc             | 1.56.5208         | TragicMC3-1.12.2-1.56.5208 - Copy.jar                | None                                     |
| L     | twilightforest       | 3.11.1021         | twilightforest-1.12.2-3.11.1021-universal - Copy.jar | None                                     |
| L     | thejungle            | 1.2006.1222       | Welcome+To+The+Jungle-1.2006.1222.jar                | None                                     |
| L     | wrd                  | 0.8.0             | Wesley's+Roguelike+Dungeons+V0.8.1 - Copy.jar        | None                                     |
| L     | midnight             | 0.3.5             | themidnight-0.3.5.jar                                | None                                     |

Loaded coremods (and transformers): 

llibrary (llibrary-core-1.0.11-1.12.2.jar)
net.ilexiconn.llibrary.server.core.plugin.LLibraryTransformer
net.ilexiconn.llibrary.server.core.patcher.LLibraryRuntimePatcher
midnight (themidnight-0.3.5.jar)
com.mushroom.midnight.core.transformer.MidnightClassTransformer
Quark Plugin (Quark-r1.6-179.jar)
vazkii.quark.base.asm.ClassTransformer
GL info: ’ Vendor: ‘ATI Technologies Inc.’ Version: ‘4.6.14736 Compatibility Profile Context 20.8.3 27.20.12027.1001’ Renderer: ‘Radeon RX 580 Series’
Launched Version: 1.12.2-forge1.12.2-14.23.5.2838
LWJGL: 2.9.4
OpenGL: Radeon RX 580 Series GL version 4.6.14736 Compatibility Profile Context 20.8.3 27.20.12027.1001, ATI Technologies Inc.
GL Caps: Using GL 1.3 multitexturing.
Using GL 1.3 texture combiners.
Using framebuffer objects because OpenGL 3.0 is supported and separate blending is supported.
Shaders are available because OpenGL 2.1 is supported.
VBOs are available because OpenGL 1.5 is supported.

Using VBOs: Yes
Is Modded: Definitely; Client brand changed to 'fml,forge'
Type: Client (map_client.txt)
Resource Packs: 
Current Language: English (US)
Profiler Position: N/A (disabled)
CPU: 6x Intel(R) Core(TM) i5-8400 CPU @ 2.80GHz

This report doesn’t really say much to me, did it work before? Did you add something recently? I would try removing mods you added recently until it works.

Also in the future, please use gist.github.com or pastebin.com to share your crash reports/ logs.

As an extra note, you haven’t even got Sponge installed here, so it’s most certainly not that. You need to go through your mods and work out which one is failing by removing one at a time. It looks like one is referencing a client class on the server.

ironchest seems to be the one that didn’t get constructued, I suppose it could be either that or cucumber - at least as a first guess.

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