Minecraft 1.12 keeps crashing with forge

Hello,

my Minecraft forge always crashes with mods in it,  for example, when i run minecraft forge with a clear mod folder under .minecraft, it runs perfectly. But when i put a mod in the mod 

folder for example ''Avatar out of the iceberg 2'' it loads the world a right before spawning into the world the game crashes! Please help...

Here the crash report: 

---- Minecraft Crash Report ----
// Why did you do that?

Time: 7/27/20 11:54 AM
Description: Exception in server tick loop

java.lang.NoSuchMethodError: net.minecraftforge.fml.relauncher.ReflectionHelper.getPrivateValue(Ljava/lang/Class;Ljava/lang/Object;Ljava/lang/String;Ljava/lang/String;)Ljava/lang/Object;
    at com.crowsofwar.avatar.common.util.AvatarUtils.<clinit>(AvatarUtils.java:61)
    at com.crowsofwar.avatar.common.data.BendingData.writeToNbt(BendingData.java:511)
    at com.crowsofwar.avatar.common.data.AvatarPlayerData.writePlayerDataToNBT(AvatarPlayerData.java:81)
    at com.crowsofwar.gorecore.data.PlayerData.writeToNBT(PlayerData.java:128)
    at com.crowsofwar.gorecore.data.PlayerData$1.writeV(PlayerData.java:61)
    at com.crowsofwar.gorecore.data.PlayerData$1.writeV(PlayerData.java:33)
    at com.crowsofwar.gorecore.util.GoreCoreNBTUtil.writeMapToNBT(GoreCoreNBTUtil.java:161)
    at com.crowsofwar.gorecore.data.WorldDataPlayers.func_189551_b(WorldDataPlayers.java:55)
    at com.crowsofwar.avatar.common.data.AvatarWorldData.func_189551_b(AvatarWorldData.java:88)
    at net.minecraft.world.storage.MapStorage.func_75747_a(SourceFile:92)
    at net.minecraft.world.storage.MapStorage.func_75744_a(SourceFile:78)
    at net.minecraft.world.WorldServer.func_73042_a(WorldServer.java:1053)
    at net.minecraft.world.WorldServer.func_73044_a(WorldServer.java:1001)
    at net.minecraft.server.MinecraftServer.func_71267_a(MinecraftServer.java:407)
    at net.minecraft.server.integrated.IntegratedServer.func_71267_a(IntegratedServer.java:252)
    at net.minecraft.server.integrated.IntegratedServer.func_71217_p(IntegratedServer.java:170)
    at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:523)
    at java.lang.Thread.run(Thread.java:745)

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

-- System Details --
Details:
    Minecraft Version: 1.12
    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: 291712720 bytes (278 MB) / 872415232 bytes (832 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: 13, tallocated: 95
    FML: MCP 9.40 Powered by Forge 14.21.1.2443 7 mods loaded, 7 mods active
    States: 'U' = Unloaded 'L' = Loaded 'C' = Constructed 'H' = Pre-initialized 'I' = Initialized 'J' = Post-initialized 'A' = Available 'D' = Disabled 'E' = Errored
    UCHIJAAAA    minecraft{1.12} [Minecraft] (minecraft.jar) 
    UCHIJAAAA    mcp{9.19} [Minecraft Coder Pack] (minecraft.jar) 
    UCHIJAAAA    FML{8.0.99.99} [Forge Mod Loader] (forge-1.12-14.21.1.2443.jar) 
    UCHIJAAAA    forge{14.21.1.2443} [Minecraft Forge] (forge-1.12-14.21.1.2443.jar) 
    UCHIJAAAA    mercurius_updater{1.0} [mercurius_updater] (MercuriusUpdater-1.12.jar) 
    UCHIJAAAA    gorecore{1.12.2-0.4.5} [GoreCore] (avatarmod-1.5.17-alpha.jar) 
    UCHIJAAAA    avatarmod{1.5.17-alpha} [Avatar Mod: Out of the Iceberg] (avatarmod-1.5.17-alpha.jar) 
    Loaded coremods (and transformers): 
    GL info: ~~ERROR~~ RuntimeException: No OpenGL context found in the current thread.
    Profiler Position: N/A (disabled)
    Player Count: 1 / 8; [EntityPlayerMP['V1gil4nt3'/433, l='P3nis', x=-90.19, y=68.00, z=259.70]]
    Type: Integrated Server (map_client.txt)
    Is Modded: Definitely; Client brand changed to 'fml,forge'