how do i downgrade lower the version of my forge?

[aiman02]

i get this message when i installed an older version of forge in 1.12.2 

 

---- Minecraft Crash Report ----

WARNING: coremods are present:
  TransformLoader (DynamicSurroundings-1.12.2-3.6.1.0.jar)
  BetterFoliageLoader (BetterFoliage-MC1.12-2.3.1.jar)
  SSLoadingPlugin (SereneSeasons-1.12.2-1.2.18-universal.jar)
  ForgelinPlugin (Forgelin-1.8.4.jar)
  Backpacked (backpacked-1.4.1-mc1.12.2.jar)
  LittlePatchingLoader (LittleTiles_v1.5.0-pre199_19_mc1.12.2.jar)
  CreativePatchingLoader (CreativeCore_v1.10.10_mc1.12.2.jar)
  MalisisCorePlugin (malisiscore-1.12.2-6.5.1.jar)
  weaponlib (mw_2.0-0.4.4.6_mc1.12.2.jar)
Contact their authors BEFORE contacting forge

// I blame Dinnerbone.

Time: 6/22/20 12:53 AM
Description: Initializing game

java.lang.NoSuchMethodError: net.minecraftforge.fml.relauncher.FMLLaunchHandler.isDeobfuscatedEnvironment()Z
    at net.minecraft.util.SoundCategory.findField(SourceFile:574)
    at net.minecraft.util.SoundCategory.<clinit>(SourceFile:39)
    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 java.lang.Class.getEnumConstantsShared(Class.java:3320)
    at java.lang.System$2.getEnumConstantsShared(System.java:1249)
    at java.util.EnumMap.getKeyUniverse(EnumMap.java:752)
    at java.util.EnumMap.<init>(EnumMap.java:138)
    at com.google.common.collect.Maps.newEnumMap(Maps.java:481)
    at net.minecraft.client.settings.GameSettings.<init>(GameSettings.java:144)
    at net.minecraft.client.Minecraft.func_71384_a(Minecraft.java:443)
    at net.minecraft.client.Minecraft.func_99999_d(Minecraft.java:377)
    at net.minecraft.client.main.Main.main(SourceFile:123)
    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:135)
    at net.minecraft.launchwrapper.Launch.main(Launch.java:28)

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

-- Head --
Thread: Client thread
Stacktrace:
    at net.minecraft.util.SoundCategory.findField(SourceFile:574)
    at net.minecraft.util.SoundCategory.<clinit>(SourceFile:39)
    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 java.lang.Class.getEnumConstantsShared(Class.java:3320)
    at java.lang.System$2.getEnumConstantsShared(System.java:1249)
    at java.util.EnumMap.getKeyUniverse(EnumMap.java:752)
    at java.util.EnumMap.<init>(EnumMap.java:138)
    at com.google.common.collect.Maps.newEnumMap(Maps.java:481)
    at net.minecraft.client.settings.GameSettings.<init>(GameSettings.java:144)
    at net.minecraft.client.Minecraft.func_71384_a(Minecraft.java:443)

-- Initialization --
Details:
Stacktrace:
    at net.minecraft.client.Minecraft.func_99999_d(Minecraft.java:377)
    at net.minecraft.client.main.Main.main(SourceFile:123)
    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:135)
    at net.minecraft.launchwrapper.Launch.main(Launch.java:28)

-- System Details --
Details:
    Minecraft Version: 1.12.2
    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: 1100432848 bytes (1049 MB) / 1308622848 bytes (1248 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: 0, tallocated: 0
    FML: 
    Loaded coremods (and transformers): 
TransformLoader (DynamicSurroundings-1.12.2-3.6.1.0.jar)
  
BetterFoliageLoader (BetterFoliage-MC1.12-2.3.1.jar)
  mods.betterfoliage.loader.BetterFoliageTransformer
SSLoadingPlugin (SereneSeasons-1.12.2-1.2.18-universal.jar)
  sereneseasons.asm.transformer.EntityRendererTransformer
  sereneseasons.asm.transformer.WorldTransformer
ForgelinPlugin (Forgelin-1.8.4.jar)
  
Backpacked (backpacked-1.4.1-mc1.12.2.jar)
  com.mrcrayfish.backpacked.asm.BackpackedTransformer
LittlePatchingLoader (LittleTiles_v1.5.0-pre199_19_mc1.12.2.jar)
  com.creativemd.littletiles.LittleTilesTransformer
CreativePatchingLoader (CreativeCore_v1.10.10_mc1.12.2.jar)
  
MalisisCorePlugin (malisiscore-1.12.2-6.5.1.jar)
  
weaponlib (mw_2.0-0.4.4.6_mc1.12.2.jar)
  com.vicmatskiv.weaponlib.core.WeaponlibClassTransformer
    Launched Version: 1.12.2-forge1.12.2-14.23.4.2759
    LWJGL: 2.9.4
    OpenGL: ~~ERROR~~ RuntimeException: No OpenGL context found in the current thread.
    GL Caps: 
    Using VBOs: ~~ERROR~~ NullPointerException: null
    Is Modded: Definitely; Client brand changed to 'fml,forge'
    Type: Client (map_client.txt)
    Resource Packs: ~~ERROR~~ NullPointerException: null
    Current Language: ~~ERROR~~ NullPointerException: null
    Profiler Position: N/A (disabled)
    CPU: <unknown>
    OptiFine Version: OptiFine_1.12.2_HD_U_F5
    OptiFine Build: 20191204-141934
    Shaders: null
    OpenGlVersion: null
    OpenGlRenderer: null
    OpenGlVendor: null
    CpuCount: 0

Edited June 21, 2020 by aiman02

[DiamondMiner88]

1.12 is no longer supported on this forum. Please update to a modern version of Minecraft to receive support.