it opens fml early loading progress but after its done it crashes (it crashes even without mods), but i tried an older versions forge(1.9.4) and it worked without a problam normal minecraft and optifine doesnt have the problem
things i tried and that didnt work:
reinstalling minecraft
reinstalling launcher
reinstalling java
reinstalling forge
crash report:
 

---- Minecraft Crash Report ----
// You should try our sister game, Minceraft!

Time: 04.08.2021 04:51
Description: Initializing game

org.spongepowered.asm.mixin.transformer.throwables.MixinTransformerError: An unexpected critical error was encountered
    at org.spongepowered.asm.mixin.transformer.MixinProcessor.applyMixins(MixinProcessor.java:363) ~[mixin-0.8.1.jar:0.8.1+unknown-b0.git-unknown] {}
    at org.spongepowered.asm.mixin.transformer.MixinTransformer.transformClass(MixinTransformer.java:223) ~[mixin-0.8.1.jar:0.8.1+unknown-b0.git-unknown] {}
    at org.spongepowered.asm.mixin.transformer.MixinTransformationHandler.processClass(MixinTransformationHandler.java:121) ~[mixin-0.8.1.jar:0.8.1+unknown-b0.git-unknown] {}
    at org.spongepowered.asm.launch.MixinLaunchPlugin.processClass(MixinLaunchPlugin.java:131) ~[mixin-0.8.1.jar:0.8.1+unknown-b0.git-unknown] {}
    at cpw.mods.modlauncher.serviceapi.ILaunchPluginService.processClassWithFlags(ILaunchPluginService.java:154) ~[modlauncher-7.0.1.jar:7.0.1+78+master.e9771d8] {}
    at cpw.mods.modlauncher.LaunchPluginHandler.offerClassNodeToPlugins(LaunchPluginHandler.java:85) ~[modlauncher-7.0.1.jar:?] {}
    at cpw.mods.modlauncher.ClassTransformer.transform(ClassTransformer.java:119) ~[modlauncher-7.0.1.jar:?] {}
    at cpw.mods.modlauncher.TransformingClassLoader$DelegatedClassLoader.findClass(TransformingClassLoader.java:256) ~[modlauncher-7.0.1.jar:?] {}
    at cpw.mods.modlauncher.TransformingClassLoader.loadClass(TransformingClassLoader.java:135) ~[modlauncher-7.0.1.jar:?] {re:classloading,re:classloading,re:classloading}
    at cpw.mods.modlauncher.TransformingClassLoader.loadClass(TransformingClassLoader.java:97) ~[modlauncher-7.0.1.jar:?] {re:classloading,re:classloading,re:classloading}
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357) ~[?:?] {}
    at net.minecraft.client.Minecraft.<init>(Minecraft.java:417) [?:?] {re:classloading,pl:accesstransformer:B,pl:runtimedistcleaner:A,re:mixin,pl:accesstransformer:B,pl:runtimedistcleaner:A}
    at net.minecraft.client.main.Main.main(Main.java:149) [?:?] {re:classloading,pl:runtimedistcleaner:A}
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:?] {}
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[?:?] {}
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:?] {}
    at java.lang.reflect.Method.invoke(Method.java:497) ~[?:?] {}
    at net.minecraftforge.fml.loading.FMLClientLaunchProvider.lambda$launchService$0(FMLClientLaunchProvider.java:51) [forge-1.16.3-34.1.0.jar:34.1] {}
    at net.minecraftforge.fml.loading.FMLClientLaunchProvider$$Lambda$412/505968231.call(Unknown Source) [forge-1.16.3-34.1.0.jar:34.1] {}
    at cpw.mods.modlauncher.LaunchServiceHandlerDecorator.launch(LaunchServiceHandlerDecorator.java:37) [modlauncher-7.0.1.jar:?] {}
    at cpw.mods.modlauncher.LaunchServiceHandler.launch(LaunchServiceHandler.java:54) [modlauncher-7.0.1.jar:?] {}
    at cpw.mods.modlauncher.LaunchServiceHandler.launch(LaunchServiceHandler.java:72) [modlauncher-7.0.1.jar:?] {}
    at cpw.mods.modlauncher.Launcher.run(Launcher.java:81) [modlauncher-7.0.1.jar:?] {}
    at cpw.mods.modlauncher.Launcher.main(Launcher.java:65) [modlauncher-7.0.1.jar:?] {}
Caused by: org.spongepowered.asm.mixin.throwables.ClassMetadataNotFoundException: com.mrcrayfish.obfuscate.common.data.SyncedPlayerData
    at org.spongepowered.asm.mixin.transformer.MixinPreProcessorStandard.transformMethod(MixinPreProcessorStandard.java:741) ~[mixin-0.8.1.jar:0.8.1+unknown-b0.git-unknown] {}
    at org.spongepowered.asm.mixin.transformer.MixinPreProcessorStandard.transform(MixinPreProcessorStandard.java:726) ~[mixin-0.8.1.jar:0.8.1+unknown-b0.git-unknown] {}
    at org.spongepowered.asm.mixin.transformer.MixinPreProcessorStandard.attach(MixinPreProcessorStandard.java:297) ~[mixin-0.8.1.jar:0.8.1+unknown-b0.git-unknown] {}
    at org.spongepowered.asm.mixin.transformer.MixinPreProcessorStandard.createContextFor(MixinPreProcessorStandard.java:267) ~[mixin-0.8.1.jar:0.8.1+unknown-b0.git-unknown] {}
    at org.spongepowered.asm.mixin.transformer.MixinInfo.createContextFor(MixinInfo.java:1271) ~[mixin-0.8.1.jar:0.8.1+unknown-b0.git-unknown] {}
    at org.spongepowered.asm.mixin.transformer.MixinApplicatorStandard.apply(MixinApplicatorStandard.java:287) ~[mixin-0.8.1.jar:0.8.1+unknown-b0.git-unknown] {}
    at org.spongepowered.asm.mixin.transformer.TargetClassContext.applyMixins(TargetClassContext.java:345) ~[mixin-0.8.1.jar:0.8.1+unknown-b0.git-unknown] {}
    at org.spongepowered.asm.mixin.transformer.MixinProcessor.applyMixins(MixinProcessor.java:569) ~[mixin-0.8.1.jar:0.8.1+unknown-b0.git-unknown] {}
    at org.spongepowered.asm.mixin.transformer.MixinProcessor.applyMixins(MixinProcessor.java:351) ~[mixin-0.8.1.jar:0.8.1+unknown-b0.git-unknown] {}
    ... 23 more

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

-- Head --
Thread: Render thread
Stacktrace:
    at org.spongepowered.asm.mixin.transformer.MixinProcessor.applyMixins(MixinProcessor.java:363) ~[mixin-0.8.1.jar:0.8.1+unknown-b0.git-unknown] {}
    at org.spongepowered.asm.mixin.transformer.MixinTransformer.transformClass(MixinTransformer.java:223) ~[mixin-0.8.1.jar:0.8.1+unknown-b0.git-unknown] {}
    at org.spongepowered.asm.mixin.transformer.MixinTransformationHandler.processClass(MixinTransformationHandler.java:121) ~[mixin-0.8.1.jar:0.8.1+unknown-b0.git-unknown] {}
    at org.spongepowered.asm.launch.MixinLaunchPlugin.processClass(MixinLaunchPlugin.java:131) ~[mixin-0.8.1.jar:0.8.1+unknown-b0.git-unknown] {}
    at cpw.mods.modlauncher.serviceapi.ILaunchPluginService.processClassWithFlags(ILaunchPluginService.java:154) ~[modlauncher-7.0.1.jar:7.0.1+78+master.e9771d8] {}
    at cpw.mods.modlauncher.LaunchPluginHandler.offerClassNodeToPlugins(LaunchPluginHandler.java:85) ~[modlauncher-7.0.1.jar:?] {}
    at cpw.mods.modlauncher.ClassTransformer.transform(ClassTransformer.java:119) ~[modlauncher-7.0.1.jar:?] {}
    at cpw.mods.modlauncher.TransformingClassLoader$DelegatedClassLoader.findClass(TransformingClassLoader.java:256) ~[modlauncher-7.0.1.jar:?] {}
    at cpw.mods.modlauncher.TransformingClassLoader.loadClass(TransformingClassLoader.java:135) ~[modlauncher-7.0.1.jar:?] {re:classloading,re:classloading,re:classloading,re:classloading}
    at cpw.mods.modlauncher.TransformingClassLoader.loadClass(TransformingClassLoader.java:97) ~[modlauncher-7.0.1.jar:?] {re:classloading,re:classloading,re:classloading,re:classloading}
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357) ~[?:?] {}
    at net.minecraft.client.Minecraft.<init>(Minecraft.java:417) ~[?:?] {re:classloading,pl:accesstransformer:B,pl:runtimedistcleaner:A,re:mixin,pl:accesstransformer:B,pl:runtimedistcleaner:A}
-- Initialization --
Details:
Stacktrace:
    at net.minecraft.client.main.Main.main(Main.java:149) [?:?] {re:classloading,pl:runtimedistcleaner:A}
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:?] {}
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[?:?] {}
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:?] {}
    at java.lang.reflect.Method.invoke(Method.java:497) ~[?:?] {}
    at net.minecraftforge.fml.loading.FMLClientLaunchProvider.lambda$launchService$0(FMLClientLaunchProvider.java:51) [forge-1.16.3-34.1.0.jar:34.1] {}
    at net.minecraftforge.fml.loading.FMLClientLaunchProvider$$Lambda$412/505968231.call(Unknown Source) [forge-1.16.3-34.1.0.jar:34.1] {}
    at cpw.mods.modlauncher.LaunchServiceHandlerDecorator.launch(LaunchServiceHandlerDecorator.java:37) [modlauncher-7.0.1.jar:?] {}
    at cpw.mods.modlauncher.LaunchServiceHandler.launch(LaunchServiceHandler.java:54) [modlauncher-7.0.1.jar:?] {}
    at cpw.mods.modlauncher.LaunchServiceHandler.launch(LaunchServiceHandler.java:72) [modlauncher-7.0.1.jar:?] {}
    at cpw.mods.modlauncher.Launcher.run(Launcher.java:81) [modlauncher-7.0.1.jar:?] {}
    at cpw.mods.modlauncher.Launcher.main(Launcher.java:65) [modlauncher-7.0.1.jar:?] {}

-- System Details --
Details:
    Minecraft Version: 1.16.3
    Minecraft Version ID: 1.16.3
    Operating System: Windows 7 (amd64) version 6.1
    Java Version: 1.8.0_51, Oracle Corporation
    Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
    Memory: 4880713768 bytes (4654 MB) / 5234491392 bytes (4992 MB) up to 5268045824 bytes (5024 MB)
    CPUs: 4
    JVM Flags: 10 total; -Xmn128M -Xmx5000M -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xss1M -XX:+UnlockExperimentalVMOptions -XX:+UseG1GC -XX:G1NewSizePercent=20 -XX:G1ReservePercent=20 -XX:MaxGCPauseMillis=50 -XX:G1HeapRegionSize=32M
    Launched Version: 1.16.3-forge-34.1.0
    Backend library: LWJGL version 3.2.2 build 10
    Backend API: AMD Radeon R7 240 GL version 4.6.14831 Compatibility Profile Context 21.5.2 27.20.20903.8001, ATI Technologies Inc.
    GL Caps: 
    Using VBOs: Yes
    Is Modded: Definitely; Client brand changed to 'forge'
    Type: Client (map_client.txt)
    CPU: <unknown>

12 minutes ago, diesieben07 said:

Seems to be an issue with "Obfuscate".

how can i fix it?

8 minutes ago, diesieben07 said:

Post the debug.log first.

where is the file located?

 

there is no such file as "debug.log" (i reinstalled minecraft after i posted this when i try to crash forge again it doesnt even open properly anymore)

its now crashes like this normal minecraft is just fine

 

right after i open the game(there is like 0.5 second gap)