A minecraft user

hi! i just created a minecraft server using forge, and it runs normally. but, i try to start it again with just one mod, it crashes immidiately. i am running the server with 6gb of ram, it's 1.12.2 and i would like to run Decocraft mod, Worldedit mod, Securitycraft mod. i'll provide crash log right here. ---- Minecraft Crash Report ---- WARNING: coremods are present: SpongeCoremod (spongeforge-1.12.2-2838-7.3.0.jar) Contact their authors BEFORE contacting forge // My bad. Time: 19/01/21 8.43 Description: Exception in server tick loop java.lang.NoClassDefFoundError: com/mia/craftstudio/IPackReaderCallback at java.lang.Class.forName0(Native Method) at java.lang.Class.forName(Unknown Source) at net.minecraftforge.fml.common.FMLModContainer.constructMod(FMLModContainer.java:539) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) at java.lang.reflect.Method.invoke(Unknown Source) 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$PerThreadQueuedDispatcher.dispatch(Dispatcher.java:116) at com.google.common.eventbus.EventBus.post(EventBus.java:217) at net.minecraftforge.fml.common.LoadController.sendEventToModContainer(LoadController.java:219) at net.minecraftforge.fml.common.LoadController.propogateStateMessage(LoadController.java:197) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) at java.lang.reflect.Method.invoke(Unknown Source) at com.google.common.eventbus.Subscriber.invokeSubscriberMethod(Subscriber.java:91) at com.google.common.eventbus.Subscriber$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$PerThreadQueuedDispatcher.dispatch(Dispatcher.java:116) at com.google.common.eventbus.EventBus.post(EventBus.java:217) at net.minecraftforge.fml.common.LoadController.redirect$zza000$forgeImpl$PostEvent(LoadController.java:568) at net.minecraftforge.fml.common.LoadController.distributeStateMessage(LoadController.java:136) at net.minecraftforge.fml.common.Loader.loadMods(Loader.java:595) at net.minecraftforge.fml.server.FMLServerHandler.beginServerLoading(FMLServerHandler.java:98) at net.minecraftforge.fml.common.FMLCommonHandler.onServerStart(FMLCommonHandler.java:333) at net.minecraft.server.dedicated.DedicatedServer.func_71197_b(DedicatedServer.java:125) at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:486) at java.lang.Thread.run(Unknown Source) Caused by: java.lang.ClassNotFoundException: com.mia.craftstudio.IPackReaderCallback at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:191) at java.lang.ClassLoader.loadClass(Unknown Source) at java.lang.ClassLoader.loadClass(Unknown Source) ... 35 more Caused by: java.lang.NullPointerException A detailed walkthrough of the error, its code path and all known details is as follows: --------------------------------------------------------------------------------------- -- Head -- Thread: Server thread Stacktrace: at java.lang.Class.forName0(Native Method) at java.lang.Class.forName(Unknown Source) at net.minecraftforge.fml.common.FMLModContainer.constructMod(FMLModContainer.java:539) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) at java.lang.reflect.Method.invoke(Unknown Source) 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$PerThreadQueuedDispatcher.dispatch(Dispatcher.java:116) at com.google.common.eventbus.EventBus.post(EventBus.java:217) at net.minecraftforge.fml.common.LoadController.sendEventToModContainer(LoadController.java:219) at net.minecraftforge.fml.common.LoadController.propogateStateMessage(LoadController.java:197) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) at java.lang.reflect.Method.invoke(Unknown Source) at com.google.common.eventbus.Subscriber.invokeSubscriberMethod(Subscriber.java:91) at com.google.common.eventbus.Subscriber$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$PerThreadQueuedDispatcher.dispatch(Dispatcher.java:116) at com.google.common.eventbus.EventBus.post(EventBus.java:217) at net.minecraftforge.fml.common.LoadController.redirect$zza000$forgeImpl$PostEvent(LoadController.java:568) at net.minecraftforge.fml.common.LoadController.distributeStateMessage(LoadController.java:136) at net.minecraftforge.fml.common.Loader.loadMods(Loader.java:595) -- Sponge PhaseTracker -- Details: Phase Stack: [Empty stack] Stacktrace: at net.minecraft.server.MinecraftServer.handler$zjg000$onCrashReport(MinecraftServer.java:4687) at net.minecraft.server.MinecraftServer.func_71230_b(MinecraftServer.java:889) at net.minecraft.server.dedicated.DedicatedServer.func_71230_b(DedicatedServer.java:371) at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:558) at java.lang.Thread.run(Unknown Source) -- System Details -- Details: Minecraft Version: 1.12.2 Operating System: Windows 10 (amd64) version 10.0 Java Version: 1.8.0_271, Oracle Corporation Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation Memory: 5301218152 bytes (5055 MB) / 6228017152 bytes (5939 MB) up to 6228017152 bytes (5939 MB) JVM Flags: 2 total; -Xms6G -Xmx6G IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0 FML: MCP 9.42 Powered by Forge 14.23.5.2854 8 mods loaded, 8 mods active States: 'U' = Unloaded 'L' = Loaded 'C' = Constructed 'H' = Pre-initialized 'I' = Initialized 'J' = Post-initialized 'A' = Available 'D' = Disabled 'E' = Errored Mods: | 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 | server.jar | e3c3d50c7c986df74c645c0ac54639741c90a557 | | LC | forge | 14.23.5.2854 | server.jar | e3c3d50c7c986df74c645c0ac54639741c90a557 | | LC | spongeapi | 7.3-7127e0882 | spongeforge-1.12.2-2838-7.3.0.jar | None | | LC | sponge | 1.12.2-7.3.0 | spongeforge-1.12.2-2838-7.3.0.jar | None | | LC | spongeforge | 1.12.2-2838-7.3.0 | spongeforge-1.12.2-2838-7.3.0.jar | None | | L | props | 2.6.3 | Decocraft-2.6.3_1.12.2.jar | None | Plugins: | State | ID | Version | Source | Signature | |:----- |:-- |:------- |:------ |:--------- | Loaded coremods (and transformers): SpongeCoremod (spongeforge-1.12.2-2838-7.3.0.jar) org.spongepowered.common.launch.transformer.SpongeSuperclassTransformer Profiler Position: N/A (disabled) Is Modded: Definitely; Server brand changed to 'fml,forge,sponge' Type: Dedicated Server (map_server.txt)