Spoiler

---- Minecraft Crash Report ----
// Surprise! Haha. Well, this is awkward.

Time: 02-01-20 15:58
Description: Exception in server tick loop

java.lang.NoClassDefFoundError: net/minecraft/world/gen/feature/BigTreeFeature
    at com.sk89q.worldedit.forge.ForgeWorldEdit.getWorld(ForgeWorldEdit.java:315) ~[?:?] {re:classloading}
    at com.sk89q.worldedit.forge.ForgeWorldEdit.onPlayerInteract(ForgeWorldEdit.java:236) ~[?:?] {re:classloading}
    at net.minecraftforge.eventbus.ASMEventHandler_5_ForgeWorldEdit_onPlayerInteract_PlayerInteractEvent.invoke(.dynamic) ~[?:?] {}
    at net.minecraftforge.eventbus.ASMEventHandler.invoke(ASMEventHandler.java:80) ~[eventbus-2.0.0-milestone.1-service.jar:?] {}
    at net.minecraftforge.eventbus.EventBus.post(EventBus.java:258) ~[eventbus-2.0.0-milestone.1-service.jar:?] {}
    at net.minecraftforge.common.ForgeHooks.onLeftClickBlock(ForgeHooks.java:777) ~[?:?] {re:classloading}
    at net.minecraft.server.management.PlayerInteractionManager.func_225416_a(PlayerInteractionManager.java:120) ~[?:?] {re:classloading}
    at net.minecraft.network.play.ServerPlayNetHandler.func_147345_a(ServerPlayNetHandler.java:833) ~[?:?] {re:classloading}
    at net.minecraft.network.play.client.CPlayerDiggingPacket.func_148833_a(SourceFile:40) ~[?:?] {re:classloading}
    at net.minecraft.network.play.client.CPlayerDiggingPacket.func_148833_a(SourceFile:10) ~[?:?] {re:classloading}
    at net.minecraft.network.PacketThreadUtil.func_225383_a(SourceFile:21) ~[?:?] {re:classloading,xf:OptiFine:default}
    at net.minecraft.network.PacketThreadUtil$$Lambda$4991/936068002.run(Unknown Source) ~[?:?] {}
    at net.minecraft.util.concurrent.TickDelayedTask.run(SourceFile:18) ~[?:?] {re:classloading}
    at net.minecraft.util.concurrent.ThreadTaskExecutor.func_213166_h(SourceFile:144) ~[?:?] {re:classloading,pl:accesstransformer:B,xf:OptiFine:default}
    at net.minecraft.util.concurrent.RecursiveEventLoop.func_213166_h(SourceFile:23) ~[?:?] {re:classloading}
    at net.minecraft.util.concurrent.ThreadTaskExecutor.func_213168_p(SourceFile:118) ~[?:?] {re:classloading,pl:accesstransformer:B,xf:OptiFine:default}
    at net.minecraft.server.MinecraftServer.func_213205_aW(MinecraftServer.java:711) ~[?:?] {re:classloading,pl:accesstransformer:B}
    at net.minecraft.server.MinecraftServer.func_213168_p(MinecraftServer.java:705) ~[?:?] {re:classloading,pl:accesstransformer:B}
    at net.minecraft.util.concurrent.ThreadTaskExecutor.func_213161_c(SourceFile:127) ~[?:?] {re:classloading,pl:accesstransformer:B,xf:OptiFine:default}
    at net.minecraft.server.MinecraftServer.func_213202_o(MinecraftServer.java:691) ~[?:?] {re:classloading,pl:accesstransformer:B}
    at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:638) [?:?] {re:classloading,pl:accesstransformer:B}
    at java.lang.Thread.run(Thread.java:745) [?:1.8.0_51] {}
Caused by: java.lang.ClassNotFoundException: net.minecraft.world.gen.feature.BigTreeFeature
    at java.lang.ClassLoader.findClass(ClassLoader.java:530) ~[?:1.8.0_51] {}
    at java.lang.ClassLoader.loadClass(ClassLoader.java:424) ~[?:1.8.0_51] {}
    at cpw.mods.modlauncher.TransformingClassLoader.loadClass(TransformingClassLoader.java:101) ~[modlauncher-5.0.0-milestone.4.jar:?] {}
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357) ~[?:1.8.0_51] {}
    ... 22 more

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

-- System Details --
Details:
    Minecraft Version: 1.15.1
    Minecraft Version ID: 1.15.1
    Operating System: Windows 10 (amd64) version 10.0
    Java Version: 1.8.0_51, Oracle Corporation
    Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
    Memory: 1011728408 bytes (964 MB) / 2147483648 bytes (2048 MB) up to 2147483648 bytes (2048 MB)
    CPUs: 8
    JVM Flags: 9 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xss1M -Xmx2G -XX:+UnlockExperimentalVMOptions -XX:+UseG1GC -XX:G1NewSizePercent=20 -XX:G1ReservePercent=20 -XX:MaxGCPauseMillis=50 -XX:G1HeapRegionSize=32M
    ModLauncher: 5.0.0-milestone.4+67+b1a340b
    ModLauncher launch target: fmlclient
    ModLauncher naming: srg
    ModLauncher services: 
        /eventbus-2.0.0-milestone.1-service.jar eventbus PLUGINSERVICE 
        /forge-1.15.1-30.0.21.jar object_holder_definalize PLUGINSERVICE 
        /forge-1.15.1-30.0.21.jar runtime_enum_extender PLUGINSERVICE 
        /accesstransformers-2.0.0-milestone.1-shadowed.jar accesstransformer PLUGINSERVICE 
        /forge-1.15.1-30.0.21.jar capability_inject_definalize PLUGINSERVICE 
        /forge-1.15.1-30.0.21.jar runtimedistcleaner PLUGINSERVICE 
        /OptiFine_1.14.4_HD_U_F4.jar OptiFine TRANSFORMATIONSERVICE 
        /forge-1.15.1-30.0.21.jar fml TRANSFORMATIONSERVICE 
    FML: 30.0
    Forge: net.minecraftforge:30.0.21
    FML Language Providers: 
        [email protected]
        minecraft@1
    Mod List: 
        forge-1.15.1-30.0.21-client.jar Minecraft {[email protected] DONE}
        forge-1.15.1-30.0.21-universal.jar Forge {[email protected] DONE}
        worldedit-forge-mc1.14.4-7.0.1.jar WorldEdit {[email protected];61bc012 DONE}
    Player Count: 1 / 8; [ServerPlayerEntity['Shen1000'/13, l='THE MERGE', x=1140.41, y=78.00, z=1146.70]]
    Data Packs: vanilla, mod:forge (incompatible), mod:worldedit (incompatible)
    Type: Integrated Server (map_client.txt)
    Is Modded: Definitely; Client brand changed to 'forge'

 

Edited January 2, 20205 yr by shen_____

You are using worldedit for 1.14.4 with 1.15.1

 

Update  the mod and see if that works

Deleted worldedit, and it worked, guess i have to play vanilla for a while ?