Minecraft Forums

So I have Vanilla installed, I install FML and then I can't install any mods otherwise or MC crashes. I know I've done FML right and I have nothing else installed. Any and all help is appreciated.

5 days later and no one has responded. Am I the only one that's having this problem??

You made sure to delete the META-INF folder?
You should probably tell us a bit more.
Mac, Windows or Linux? What version of Java do you have? What mods did you try to install? etc. etc.


Also a crash report would be helpful.

I always delete META-INF. Every version of Minecraft I've had up til now has worked with mods. Unless with 1.5.2 there's some new thing I'm supposed to do that i haven't found, it all seems pretty bizarre. I could supply a hundred crash reports of a hundred different mods that I could try, it just always messes up after I install one mod once I have FML. I've currently tried just over a dozen mods, and every time MC crashes, I back it up a step. Unfortunately, it's the same step which is back to Vanilla with FML. I have up to date Java and all that, too. I'm running Win7 and each of the mods I've tried are popular, constantly updated ones like Too Many Items, Too Much TNT, and others, all 1.5.2 and FML compatible. Just for kicks, here's MC with FML and trying the mod, Metallurgy.

---- Minecraft Crash Report ----
// On the bright side, I bought you a teddy bear!

Time: 6/18/13 7:11 PM
Description: Failed to start game

cpw.mods.fml.common.LoaderException: java.lang.NoClassDefFoundError: net/minecraftforge/common/Configuration
    at cpw.mods.fml.common.LoadController.transition(LoadController.java:117)
    at cpw.mods.fml.common.Loader.loadMods(Loader.java:486)
    at cpw.mods.fml.client.FMLClientHandler.beginMinecraftLoading(FMLClientHandler.java:161)
    at net.minecraft.client.Minecraft.a(Minecraft.java:313)
    at asq.a(SourceFile:56)
    at net.minecraft.client.Minecraft.run(Minecraft.java:622)
    at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.NoClassDefFoundError: net/minecraftforge/common/Configuration
    at shadow.mods.metallurgy.CoreConfig.init(CoreConfig.java:80)
    at shadow.mods.metallurgy.MetallurgyCore.preInit(MetallurgyCore.java:65)
    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 cpw.mods.fml.common.FMLModContainer.handleModStateEvent(FMLModContainer.java:483)
    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.EventHandler.handleEvent(EventHandler.java:69)
    at com.google.common.eventbus.SynchronizedEventHandler.handleEvent(SynchronizedEventHandler.java:45)
    at com.google.common.eventbus.EventBus.dispatch(EventBus.java:317)
    at com.google.common.eventbus.EventBus.dispatchQueuedEvents(EventBus.java:300)
    at com.google.common.eventbus.EventBus.post(EventBus.java:268)
    at cpw.mods.fml.common.LoadController.propogateStateMessage(LoadController.java:140)
    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.EventHandler.handleEvent(EventHandler.java:69)
    at com.google.common.eventbus.SynchronizedEventHandler.handleEvent(SynchronizedEventHandler.java:45)
    at com.google.common.eventbus.EventBus.dispatch(EventBus.java:317)
    at com.google.common.eventbus.EventBus.dispatchQueuedEvents(EventBus.java:300)
    at com.google.common.eventbus.EventBus.post(EventBus.java:268)
    at cpw.mods.fml.common.LoadController.distributeStateMessage(LoadController.java:83)
    at cpw.mods.fml.common.Loader.loadMods(Loader.java:485)
    ... 5 more
Caused by: java.lang.ClassNotFoundException: net.minecraftforge.common.Configuration
    at cpw.mods.fml.relauncher.RelaunchClassLoader.findClass(RelaunchClassLoader.java:179)
    at java.lang.ClassLoader.loadClass(Unknown Source)
    at java.lang.ClassLoader.loadClass(Unknown Source)
    ... 33 more
Caused by: java.lang.NullPointerException
    at cpw.mods.fml.relauncher.RelaunchClassLoader.findClass(RelaunchClassLoader.java:172)
    ... 35 more


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

-- System Details --
Details:
    Minecraft Version: 1.4.6
    Operating System: Windows 7 (x86) version 6.1
    Java Version: 1.7.0_21, Oracle Corporation
    Java VM Version: Java HotSpot(TM) Client VM (mixed mode), Oracle Corporation
    Memory: 408594568 bytes (389 MB) / 518979584 bytes (494 MB) up to 1037959168 bytes (989 MB)
    JVM Flags: 2 total; -Xms512m -Xmx1024m
    AABB Pool Size: 0 (0 bytes; 0 MB) allocated, 0 (0 bytes; 0 MB) used
    Suspicious classes: FML is installed
    IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
    FML: MCP v7.25 FML v4.6.15.514 3 mods loaded, 3 mods active
    mcp [Minecraft Coder Pack] (minecraft.jar) Unloaded->Constructed->Pre-initialized
    FML [Forge Mod Loader] (coremods) Unloaded->Constructed->Pre-initialized
    MetallurgyCore [Metallurgy Core] (minecraft.jar) Unloaded->Constructed->Errored
    LWJGL: 2.4.2
    OpenGL: Intel(R) HD Graphics GL version 2.1.0 - Build 8.15.10.2622, Intel
    Is Modded: Definitely; Client brand changed to 'fml'
    Type: Client (map_client.txt)
    Texture Pack: Default
    Profiler Position: N/A (disabled)
    Vec3 Pool Size: ~~ERROR~~ NullPointerException: null

It's probably the mods that you are installing, some of the mods are compatible with Forge and some aren't. Try checking the mod information and see if it needs Forge or Modloader, and also be sure to delete the META-INF folder.

Quote from RickyM87

It's probably the mods that you are installing, some of the mods are compatible with Forge and some aren't. Try checking the mod information and see if it needs Forge or Modloader, and also be sure to delete the META-INF folder.

I always double check to see if it's FML compatible. I've been downtrodden so many times because some mods just won't work with FML. And I always, ALWAYS, delete the META-INF folder whenever I install a mod that includes it as my vanilla jar doesn't have it.

Still nada, huh? Any ideas at this point are more effective than what I have now...

Are you installing Forge, or just FML. In your example, Metallurgy requires Forge to run, not just FML.

That's where I got it from. I'm currently waiting for it to crash again and give me a report. I'm seriously running FML and just added TMI. And it's blackscreening. I'm not joking about this. I know how to add mods and run them, this is messing with me so bad.

EDIT: So the reason the crash report only mentions me running FML is because everytime I add a new mod, it blackscreens, so no crash report. I still need help.