I downloaded the latest version and its crashing with the loader 10.8.
I had to use older version 0.26.0+1.16

We just released .3 which may help? Please provide a crash report if it still happens.

Tested with fabric-api-0.29.3+1.16.jar still crashing with no crash report, exit code: 0

Still Happens. MC 1.16.4 No problem with V 0.28.4. Minecraft log, no crash report:

MultiMC version: 0.6.11-1430

Failed to start Minecraft:
java.lang.reflect.InvocationTargetException
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 org.multimc.onesix.OneSixLauncher.launchWithMainClass(OneSixLauncher.java:196)
at org.multimc.onesix.OneSixLauncher.launch(OneSixLauncher.java:231)
at org.multimc.EntryPoint.listen(EntryPoint.java:143)
at org.multimc.EntryPoint.main(EntryPoint.java:34)
Caused by: java.lang.RuntimeException: java.lang.reflect.InvocationTargetException
at net.fabricmc.loader.game.MinecraftGameProvider.launch(MinecraftGameProvider.java:226)
at net.fabricmc.loader.launch.knot.Knot.init(Knot.java:141)
at net.fabricmc.loader.launch.knot.KnotClient.main(KnotClient.java:27)
... 8 more
Caused by: java.lang.reflect.InvocationTargetException
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.fabricmc.loader.game.MinecraftGameProvider.launch(MinecraftGameProvider.java:224)
... 10 more
Caused by: org.spongepowered.asm.mixin.transformer.throwables.MixinTransformerError: An unexpected critical error was encountered
at org.spongepowered.asm.mixin.transformer.MixinProcessor.applyMixins(MixinProcessor.java:363)
at org.spongepowered.asm.mixin.transformer.MixinTransformer.transformClass(MixinTransformer.java:208)
at org.spongepowered.asm.mixin.transformer.MixinTransformer.transformClassBytes(MixinTransformer.java:178)
at org.spongepowered.asm.mixin.transformer.FabricMixinTransformerProxy.transformClassBytes(FabricMixinTransformerProxy.java:23)
at net.fabricmc.loader.launch.knot.KnotClassDelegate.getPostMixinClassByteArray(KnotClassDelegate.java:157)
at net.fabricmc.loader.launch.knot.KnotClassLoader.loadClass(KnotClassLoader.java:150)
at java.lang.ClassLoader.loadClass(Unknown Source)
at net.optifine.reflect.Reflector.(Reflector.java:286)
at net.minecraft.class_128.method_559(class_128.java:101)
at net.minecraft.class_128.(class_128.java:54)
at net.minecraft.class_128.method_24305(class_128.java:425)
at net.minecraft.client.main.Main.main(Main.java:135)
... 15 more
Caused by: org.spongepowered.asm.mixin.injection.throwables.InjectionError: Critical injection failure: Callback method onRenderParticles(Lorg/spongepowered/asm/mixin/injection/callback/CallbackInfo;)V in fabric-rendering-v1.mixins.json:MixinWorldRenderer failed injection check, (0/1) succeeded. Scanned 1 target(s). Using refmap fabric-rendering-v1-refmap.json
at org.spongepowered.asm.mixin.injection.struct.InjectionInfo.postInject(InjectionInfo.java:408)
at org.spongepowered.asm.mixin.transformer.MixinTargetContext.applyInjections(MixinTargetContext.java:1291)
at org.spongepowered.asm.mixin.transformer.MixinApplicatorStandard.applyInjections(MixinApplicatorStandard.java:1042)
at org.spongepowered.asm.mixin.transformer.MixinApplicatorStandard.applyMixin(MixinApplicatorStandard.java:395)
at org.spongepowered.asm.mixin.transformer.MixinApplicatorStandard.apply(MixinApplicatorStandard.java:320)
at org.spongepowered.asm.mixin.transformer.TargetClassContext.applyMixins(TargetClassContext.java:345)
at org.spongepowered.asm.mixin.transformer.MixinProcessor.applyMixins(MixinProcessor.java:569)
at org.spongepowered.asm.mixin.transformer.MixinProcessor.applyMixins(MixinProcessor.java:351)
... 26 more
Exiting with -1
Process exited with code -1.

I Have this same issue also, it apparently is something to do with the rendering (Particles more precisely), as u can see in my logs.

Are you running your mods with optifabric?

I am

i suspected that it was optifabric the is the issue, but i havent tested that out yet so yeah

Yea it's a problem with optifabric atm

The issue was with the optifabric older version optifabric-1.8.5.jar, tested with the latest optifabric-1.8.16.jar and fabric-api-0.29.3+1.16.jar and is working fine.