Tekkit Failed to register id -23

[Nebzz]

---- Minecraft Crash Report ----
// Sorry :(

Time: 8/1/20 12:04 PM
Description: Ticking screen

java.lang.IllegalArgumentException: Failed to register dimension for id -23, provider type 13 does not exist
    at net.minecraftforge.common.DimensionManager.registerDimension(DimensionManager.java:123)
    at net.minecraftforge.common.network.packet.DimensionRegisterPacket.execute(DimensionRegisterPacket.java:64)
    at net.minecraftforge.common.network.ForgePacketHandler.onPacketData(ForgePacketHandler.java:23)
    at cpw.mods.fml.common.network.NetworkRegistry.handlePacket(NetworkRegistry.java:255)
    at cpw.mods.fml.common.network.NetworkRegistry.handleCustomPacket(NetworkRegistry.java:245)
    at cpw.mods.fml.common.network.FMLNetworkHandler.handlePacket250Packet(FMLNetworkHandler.java:85)
    at net.minecraft.client.multiplayer.NetClientHandler.func_72501_a(NetClientHandler.java:1651)
    at net.minecraft.network.packet.Packet250CustomPayload.func_73279_a(SourceFile:61)
    at net.minecraft.network.TcpConnection.func_74428_b(TcpConnection.java:462)
    at net.minecraft.client.multiplayer.NetClientHandler.func_72551_d(NetClientHandler.java:281)
    at net.minecraft.client.multiplayer.GuiConnecting.func_73876_c(GuiConnecting.java:51)
    at net.minecraft.client.Minecraft.func_71407_l(Minecraft.java:1580)
    at net.minecraft.client.Minecraft.func_71411_J(Minecraft.java:910)
    at net.minecraft.client.Minecraft.func_99999_d(Minecraft.java:838)
    at net.minecraft.client.main.Main.main(SourceFile:101)
    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:131)
    at net.minecraft.launchwrapper.Launch.main(Launch.java:27)

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

-- Head --
Stacktrace:
    at net.minecraftforge.common.DimensionManager.registerDimension(DimensionManager.java:123)
    at net.minecraftforge.common.network.packet.DimensionRegisterPacket.execute(DimensionRegisterPacket.java:64)
    at net.minecraftforge.common.network.ForgePacketHandler.onPacketData(ForgePacketHandler.java:23)
    at cpw.mods.fml.common.network.NetworkRegistry.handlePacket(NetworkRegistry.java:255)
    at cpw.mods.fml.common.network.NetworkRegistry.handleCustomPacket(NetworkRegistry.java:245)
    at cpw.mods.fml.common.network.FMLNetworkHandler.handlePacket250Packet(FMLNetworkHandler.java:85)
    at net.minecraft.client.multiplayer.NetClientHandler.func_72501_a(NetClientHandler.java:1651)
    at net.minecraft.network.packet.Packet250CustomPayload.func_73279_a(SourceFile:61)
    at net.minecraft.network.TcpConnection.func_74428_b(TcpConnection.java:462)
    at net.minecraft.client.multiplayer.NetClientHandler.func_72551_d(NetClientHandler.java:281)
    at net.minecraft.client.multiplayer.GuiConnecting.func_73876_c(GuiConnecting.java:51)

-- Affected screen --
Details:
    Screen name: net.minecraft.client.multiplayer.GuiConnecting
Stacktrace:
    at net.minecraft.client.Minecraft.func_71407_l(Minecraft.java:1580)
    at net.minecraft.client.Minecraft.func_71411_J(Minecraft.java:910)
    at net.minecraft.client.Minecraft.func_99999_d(Minecraft.java:838)
    at net.minecraft.client.main.Main.main(SourceFile:101)
    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:131)
    at net.minecraft.launchwrapper.Launch.main(Launch.java:27)

-- System Details --
Details:
    Minecraft Version: 1.6.4
    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: 149546640 bytes (142 MB) / 234881024 bytes (224 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
    AABB Pool Size: 0 (0 bytes; 0 MB) allocated, 0 (0 bytes; 0 MB) used
    Suspicious classes: FML and Forge are installed
    IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
    FML: MCP v8.11 FML v6.4.50.1,345 Minecraft Forge 9.11.1.1345 3 mods loaded, 3 mods active
    mcp{8.09} [Minecraft Coder Pack] (minecraft.jar) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available
    FML{6.4.50.1,345} [Forge Mod Loader] (minecraftforge-9.11.1.1345.jar) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available
    Forge{9.11.1.1345} [Minecraft Forge] (minecraftforge-9.11.1.1345.jar) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available
    Launched Version: 1.6.4-Forge9.11.1.1345
    LWJGL: 2.9.0
    OpenGL: AMD Radeon RX 5700 XT GL version 4.6.13596 Compatibility Profile Context 20.5.1 27.20.1017.1011, ATI Technologies Inc.
    Is Modded: Definitely; Client brand changed to 'fml,forge'
    Type: Client (map_client.txt)
    Resource Pack: Default
    Current Language: English (US)
    Profiler Position: N/A (disabled)
    Vec3 Pool Size: ~~ERROR~~ NullPointerException: null

crash-2020-08-01_12.04.46-client.txt

[TerdyTheTerd]

Based on the log I am assuming you are connecting to a server, in that case there's a high probability this is caused by different configs on the server <-> client. Make sure the client has the same configs, especially for id's, as the server is running.