So my minecraft instantly crashes when opening/creating world on singleplayer. I´m using MC 1.7.2 and I tried with Latest and Recomended forge versions.

 

The only mod that I´m using is LegacyJavaFixer because if I don´t use it my game will not open. This is one of the crash reports:

 

--- Minecraft Crash Report ----
// Sorry

Time: 02/02/18 19:16
Description: Starting integrated server

java.lang.NoClassDefFoundError: com/mojang/authlib/yggdrasil/YggdrasilAuthenticationService
    at net.minecraft.server.MinecraftServer.<init>(MinecraftServer.java:143)
    at net.minecraft.server.integrated.IntegratedServer.<init>(IntegratedServer.java:45)
    at net.minecraft.client.Minecraft.func_71371_a(Minecraft.java:2041)
    at cpw.mods.fml.client.FMLClientHandler.tryLoadExistingWorld(FMLClientHandler.java:669)
    at net.minecraft.client.gui.GuiSelectWorld.func_146615_e(GuiSelectWorld.java:183)
    at net.minecraft.client.gui.GuiSelectWorld$List.func_148144_a(GuiSelectWorld.java:257)
    at net.minecraft.client.gui.GuiSlot.func_148128_a(GuiSlot.java:209)
    at net.minecraft.client.gui.GuiSelectWorld.func_73863_a(GuiSelectWorld.java:216)
    at net.minecraft.client.renderer.EntityRenderer.func_78480_b(EntityRenderer.java:1061)
    at net.minecraft.client.Minecraft.func_71411_J(Minecraft.java:944)
    at net.minecraft.client.Minecraft.func_99999_d(Minecraft.java:835)
    at net.minecraft.client.main.Main.main(SourceFile:103)
    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:134)
    at net.minecraft.launchwrapper.Launch.main(Launch.java:28)
    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 kml.game.GameStarter.main(GameStarter.java:46)
Caused by: java.lang.ClassNotFoundException: com.mojang.authlib.yggdrasil.YggdrasilAuthenticationService
    at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:188)
    at java.lang.ClassLoader.loadClass(Unknown Source)
    at java.lang.ClassLoader.loadClass(Unknown Source)
    ... 23 more
Caused by: java.lang.IllegalArgumentException
    at org.objectweb.asm.ClassReader.<init>(Unknown Source)
    at org.objectweb.asm.ClassReader.<init>(Unknown Source)
    at cpw.mods.fml.common.asm.transformers.deobf.FMLDeobfuscatingRemapper.findAndMergeSuperMaps(FMLDeobfuscatingRemapper.java:347)
    at cpw.mods.fml.common.asm.transformers.deobf.FMLDeobfuscatingRemapper.getMethodMap(FMLDeobfuscatingRemapper.java:324)
    at cpw.mods.fml.common.asm.transformers.deobf.FMLDeobfuscatingRemapper.mapMethodName(FMLDeobfuscatingRemapper.java:297)
    at org.objectweb.asm.commons.RemappingMethodAdapter.visitMethodInsn(Unknown Source)
    at org.objectweb.asm.ClassReader.a(Unknown Source)
    at org.objectweb.asm.ClassReader.b(Unknown Source)
    at org.objectweb.asm.ClassReader.accept(Unknown Source)
    at org.objectweb.asm.ClassReader.accept(Unknown Source)
    at cpw.mods.fml.common.asm.transformers.DeobfuscationTransformer.transform(DeobfuscationTransformer.java:37)
    at net.minecraft.launchwrapper.LaunchClassLoader.runTransformers(LaunchClassLoader.java:276)
    at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:174)
    ... 25 more

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

-- Head --
Stacktrace:
    at net.minecraft.server.MinecraftServer.<init>(MinecraftServer.java:143)
    at net.minecraft.server.integrated.IntegratedServer.<init>(IntegratedServer.java:45)

-- Starting integrated server --
Details:
    Level ID: Alv
    Level Name: Alv
Stacktrace:
    at net.minecraft.client.Minecraft.func_71371_a(Minecraft.java:2041)
    at cpw.mods.fml.client.FMLClientHandler.tryLoadExistingWorld(FMLClientHandler.java:669)
    at net.minecraft.client.gui.GuiSelectWorld.func_146615_e(GuiSelectWorld.java:183)
    at net.minecraft.client.gui.GuiSelectWorld$List.func_148144_a(GuiSelectWorld.java:257)
    at net.minecraft.client.gui.GuiSlot.func_148128_a(GuiSlot.java:209)
    at net.minecraft.client.gui.GuiSelectWorld.func_73863_a(GuiSelectWorld.java:216)

-- Screen render details --
Details:
    Screen name: net.minecraft.client.gui.GuiMainMenu
    Mouse location: Scaled: (184, 155). Absolute: (552, 433)
    Screen size: Scaled: (534, 300). Absolute: (1600, 900). Scale factor of 3
Stacktrace:
    at net.minecraft.client.renderer.EntityRenderer.func_78480_b(EntityRenderer.java:1061)
    at net.minecraft.client.Minecraft.func_71411_J(Minecraft.java:944)
    at net.minecraft.client.Minecraft.func_99999_d(Minecraft.java:835)
    at net.minecraft.client.main.Main.main(SourceFile:103)
    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:134)
    at net.minecraft.launchwrapper.Launch.main(Launch.java:28)
    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 kml.game.GameStarter.main(GameStarter.java:46)

-- System Details --
Details:
    Minecraft Version: 1.7.2
    Operating System: Windows 10 (amd64) version 10.0
    Java Version: 1.8.0_151, Oracle Corporation
    Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
    Memory: 77705768 bytes (74 MB) / 173015040 bytes (165 MB) up to 2102919168 bytes (2005 MB)
    JVM Flags: 2 total; -Xmx2G -Xmn128M
    AABB Pool Size: 0 (0 bytes; 0 MB) allocated, 0 (0 bytes; 0 MB) used
    IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
    FML: MCP v9.03 FML v7.2.211.1121 Minecraft Forge 10.12.2.1121 3 mods loaded, 3 mods active
    mcp{9.03} [Minecraft Coder Pack] (minecraft.jar) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available
    FML{7.2.211.1121} [Forge Mod Loader] (forge-1.7.2-10.12.2.1121.jar) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available
    Forge{10.12.2.1121} [Minecraft Forge] (forge-1.7.2-10.12.2.1121.jar) Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available
    Launched Version: 1.7.2-Forge10.12.2.1121
    LWJGL: 2.9.0
    OpenGL: AMD Radeon (TM) R7 370 Series GL version 4.5.13506 Compatibility Profile Context 23.20.15002.11, ATI Technologies Inc.
    Is Modded: Definitely; Client brand changed to 'fml,forge'
    Type: Client (map_client.txt)
    Resource Packs: []
    Current Language: Español (Argentino)
    Profiler Position: N/A (disabled)
    Vec3 Pool Size: ~~ERROR~~ NullPointerException: null
    Anisotropic Filtering: Off (1)

 

Hope this helps and sorry if I missed something.

 

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Sad