java.lang.NoClassDefFoundError: net/fabricmc/tinyremapper/IMappingProvider
at me.modmuss50.optifabric.mod.OptifabricSetup.run(OptifabricSetup.java:41)
at java.base/java.util.ArrayList.forEach(ArrayList.java:1511)
at com.chocohead.mm.Plugin.getMixins(Plugin.java:340)
at org.spongepowered.asm.mixin.transformer.PluginHandle.getMixins(PluginHandle.java:128)
at org.spongepowered.asm.mixin.transformer.MixinConfig.postInitialise(MixinConfig.java:796)
at org.spongepowered.asm.mixin.transformer.MixinProcessor.prepareConfigs(MixinProcessor.java:568)
at org.spongepowered.asm.mixin.transformer.MixinProcessor.select(MixinProcessor.java:462)
at org.spongepowered.asm.mixin.transformer.MixinProcessor.checkSelect(MixinProcessor.java:438)
at org.spongepowered.asm.mixin.transformer.MixinProcessor.applyMixins(MixinProcessor.java:290)
at org.spongepowered.asm.mixin.transformer.MixinTransformer.transformClass(MixinTransformer.java:234)
at org.spongepowered.asm.mixin.transformer.MixinTransformer.transformClassBytes(MixinTransformer.java:202)
at net.fabricmc.loader.impl.launch.knot.KnotClassDelegate.getPostMixinClassByteArray(KnotClassDelegate.java:422)
at net.fabricmc.loader.impl.launch.knot.KnotClassDelegate.tryLoadClass(KnotClassDelegate.java:323)
at net.fabricmc.loader.impl.launch.knot.KnotClassDelegate.loadClass(KnotClassDelegate.java:218)
at net.fabricmc.loader.impl.launch.knot.KnotClassLoader.loadClass(KnotClassLoader.java:119)
at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:519)
at java.base/java.lang.Class.forName0(Native Method)
at java.base/java.lang.Class.forName(Class.java:466)
at net.fabricmc.loader.impl.util.DefaultLanguageAdapter.create(DefaultLanguageAdapter.java:50)
at net.fabricmc.loader.impl.entrypoint.EntrypointStorage$NewEntry.getOrCreate(EntrypointStorage.java:117)
at net.fabricmc.loader.impl.entrypoint.EntrypointContainerImpl.getEntrypoint(EntrypointContainerImpl.java:53)
at net.fabricmc.loader.impl.FabricLoaderImpl.invokeEntrypoints(FabricLoaderImpl.java:384)
at net.fabricmc.loader.impl.launch.knot.Knot.init(Knot.java:160)
at net.fabricmc.loader.impl.launch.knot.Knot.launch(Knot.java:68)
at net.fabricmc.loader.impl.launch.knot.KnotClient.main(KnotClient.java:23)
Caused by: java.lang.ClassNotFoundException: net.fabricmc.tinyremapper.IMappingProvider
at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:636)
at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:519)
at net.fabricmc.loader.impl.launch.knot.KnotClassDelegate.loadClass(KnotClassDelegate.java:226)
at net.fabricmc.loader.impl.launch.knot.KnotClassLoader.loadClass(KnotClassLoader.java:119)
at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:519)
... 25 more

Then you can't be running Fabric Loader 0.14.25 or you wouldn't be getting that error message. Check to make sure you are using Fabric API 0.42.0, Optifabric 1.13.16, Optifine G8, and lastly look at the Profile set in the Launcher to make sure it reads: release fabric-loader-0.14.25-1.16.5

Then you can't be running Fabric Loader 0.14.25 or you wouldn't be getting that error message. Check to make sure you are using Fabric API 0.42.0, Optifabric 1.13.16, Optifine G8, and lastly look at the Profile set in the Launcher to make sure it reads: release fabric-loader-0.14.25-1.16.5

Is the Optifine HD U 8 version suitable?

Тогда вы не сможете использовать Fabric Loader 0.14.25, иначе вы не получите это сообщение об ошибке. Убедитесь, что вы используете Fabric API 0.42.0, Optifabric 1.13.16, Optifine G8, и, наконец, посмотрите на профиль, установленный в панели запуска, чтобы убедиться, что он гласит: Release Fabric-Loader-0.14.25-1.16.5

I checked everything according to your comment, but maybe it’s because I’m using Legacy Launcher?

If you mean the G8 version as there is no U 8 version, they yes otherwise I wouldn't use whatever version that is.

If you mean the G8 version as there is no U 8 version, they yes otherwise I wouldn't use whatever version that is.

thank you, yes, I meant HD U G8, but your help did not help me

What do you mean by legacy launcher? If you can provide a screenshot of the launcher I might be able to help get you sorted out.

Legacy Launcher is a pirated/illegal Minecraft launcher.