Codprimus

I had the same problem, to solve it i copied over my saves and re-installed minecraft. After this i installed forge and bam, works like a dream.

I figured it out, turns out i had some older mod files in my .minecraft folder after i reset the folder everything was fine

I have followed 5 different tutorials and tried everything, but whenever i try to load a world with forge it says "shutting down internal server" and crashes. Can anybody help ---- Minecraft Crash Report ---- // On the bright side, I bought you a teddy bear! Time: 12/08/13 10:10 Description: Unexpected error java.lang.ClassCastException: net.minecraft.client.entity.EntityClientPlayerMP cannot be cast to cpw.mods.fml.common.network.Player at cpw.mods.fml.common.network.NetworkRegistry.handleCustomPacket(NetworkRegistry.java:245) at cpw.mods.fml.common.network.FMLNetworkHandler.handlePacket250Packet(FMLNetworkHandler.java:84) at net.minecraft.client.multiplayer.NetClientHandler.func_72501_a(NetClientHandler.java:1647) at net.minecraft.network.packet.Packet250CustomPayload.func_73279_a(SourceFile:61) at net.minecraft.network.MemoryConnection.func_74428_b(MemoryConnection.java:89) at net.minecraft.client.Minecraft.func_71407_l(Minecraft.java:1953) at net.minecraft.client.Minecraft.func_71411_J(Minecraft.java:898) at net.minecraft.client.Minecraft.func_99999_d(Minecraft.java:826) at net.minecraft.client.main.Main.main(SourceFile:101) 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 net.minecraft.launchwrapper.Launch.launch(Launch.java:57) at net.minecraft.launchwrapper.Launch.main(Launch.java:18) A detailed walkthrough of the error, its code path and all known details is as follows: --------------------------------------------------------------------------------------- -- Head -- Stacktrace: at cpw.mods.fml.common.network.NetworkRegistry.handleCustomPacket(NetworkRegistry.java:245) at cpw.mods.fml.common.network.FMLNetworkHandler.handlePacket250Packet(FMLNetworkHandler.java:84) at net.minecraft.client.multiplayer.NetClientHandler.func_72501_a(NetClientHandler.java:1647) at net.minecraft.network.packet.Packet250CustomPayload.func_73279_a(SourceFile:61) at net.minecraft.network.MemoryConnection.func_74428_b(MemoryConnection.java:89) -- Affected level -- Details: Level name: MpServer All players: 1 total; [EntityClientPlayerMP['beneto12'/140, l='MpServer', x=8.50, y=66.62, z=8.50]] Chunk stats: MultiplayerChunkCache: 0 Level seed: 0 Level generator: ID 01 - flat, ver 0. Features enabled: false Level generator options: Level spawn location: World: (8,64,, Chunk: (at 8,4,8 in 0,0; contains blocks 0,0,0 to 15,255,15), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,0,0 to 511,255,511) Level time: 0 game time, 0 day time Level dimension: 0 Level storage version: 0x00000 - Unknown? Level weather: Rain time: 0 (now: false), thunder time: 0 (now: false) Level game mode: Game mode: creative (ID 1). Hardcore: false. Cheats: false Forced entities: 1 total; [EntityClientPlayerMP['beneto12'/140, l='MpServer', x=8.50, y=66.62, z=8.50]] Retry entities: 0 total; [] Server brand: fml,forge Server type: Integrated singleplayer server Stacktrace: at net.minecraft.client.multiplayer.WorldClient.func_72914_a(WorldClient.java:440) at net.minecraft.client.Minecraft.func_71396_d(Minecraft.java:2298) at net.minecraft.client.Minecraft.func_99999_d(Minecraft.java:851) at net.minecraft.client.main.Main.main(SourceFile:101) 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 net.minecraft.launchwrapper.Launch.launch(Launch.java:57) at net.minecraft.launchwrapper.Launch.main(Launch.java:18) -- System Details -- Details: Minecraft Version: 1.6.2 Operating System: Windows 8 (x86) version 6.2 Java Version: 1.7.0_25, Oracle Corporation Java VM Version: Java HotSpot Client VM (mixed mode, sharing), Oracle Corporation Memory: 187421312 bytes (178 MB) / 356843520 bytes (340 MB) up to 518979584 bytes (494 MB) JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx512M AABB Pool Size: 4625 (259000 bytes; 0 MB) allocated, 4625 (259000 bytes; 0 MB) used Suspicious classes: FML and Forge are installed IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0 FML: MCP v8.04 FML v6.2.43.828 Minecraft Forge 9.10.0.828 3 mods loaded, 3 mods active mcp{8.04} [Minecraft Coder Pack] (minecraft.jar) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available->Available->Available FML{6.2.43.828} [Forge Mod Loader] (coremods) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available->Available->Available Forge{9.10.0.828} [Minecraft Forge] (coremods) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available->Available->Available Launched Version: 1.6.2-Forge9.10.0.828 LWJGL: 2.9.0 OpenGL: AMD Radeon HD 7340G GL version 4.2.11764 Compatibility Profile Context, ATI Technologies Inc. Is Modded: Definitely; Client brand changed to 'fml,forge' Type: Client (map_client.txt) Resource Pack: Default Current Language: Pirate Speak (PIRATE) Profiler Position: N/A (disabled) Vec3 Pool Size: 0 (0 bytes; 0 MB) allocated, 0 (0 bytes; 0 MB) used