I installed the new update from 25/03/25 yesterday and after that when I try to start Minecraft now it immediatly crashes with the logs:

at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[?:1.8.0_51]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[?:1.8.0_51]
at java.lang.reflect.Method.invoke(Method.java:497) ~[?:1.8.0_51]
at net.minecraft.launchwrapper.Launch.launch(Launch.java:135) [launchwrapper-1.12.jar:?]
at net.minecraft.launchwrapper.Launch.main(Launch.java:28) [launchwrapper-1.12.jar:?]

Caused by: java.lang.NoClassDefFoundError: net/minecraft/client/Minecraft
at net.minecraft.client.main.Main.main(SourceFile:38) ~[Main.class:?]
... 6 more
Caused by: java.lang.ClassNotFoundException: net.minecraft.client.Minecraft
at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:191) ~[launchwrapper-1.12.jar:?]
at java.lang.ClassLoader.loadClass(ClassLoader.java:424) ~[?:1.8.0_51]
at java.lang.ClassLoader.loadClass(ClassLoader.java:357) ~[?:1.8.0_51]
at net.minecraft.client.main.Main.main(SourceFile:38) ~[Main.class:?]
... 6 more
Caused by: org.spongepowered.asm.mixin.transformer.throwables.ReEntrantTransformerError: Re-entrance error.
at org.spongepowered.asm.mixin.transformer.MixinProcessor.applyMixins(MixinProcessor.java:366) ~[!mixinbooter-10.6.jar:?]
at org.spongepowered.asm.mixin.transformer.MixinTransformer.transformClass(MixinTransformer.java:240) ~[!mixinbooter-10.6.jar:?]
at org.spongepowered.asm.mixin.transformer.MixinTransformer.transformClassBytes(MixinTransformer.java:208) ~[!mixinbooter-10.6.jar:?]
at org.spongepowered.asm.mixin.transformer.Proxy.transform(Proxy.java:71) ~[!mixinbooter-10.6.jar:?]
at net.minecraft.launchwrapper.LaunchClassLoader.runTransformers(LaunchClassLoader.java:279) ~[launchwrapper-1.12.jar:?]
at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:176) ~[launchwrapper-1.12.jar:?]
at java.lang.ClassLoader.loadClass(ClassLoader.java:424) ~[?:1.8.0_51]
at java.lang.ClassLoader.loadClass(ClassLoader.java:357) ~[?:1.8.0_51]
at net.minecraft.client.main.Main.main(SourceFile:38) ~[Main.class:?]
... 6 more

Can anyone please help me?

You seem to be using a very old version of Java 8 (1.8.0_51):

at java.lang.ClassLoader.loadClass(ClassLoader.java:424) ~[?:1.8.0_51]
at java.lang.ClassLoader.loadClass(ClassLoader.java:357) ~[?:1.8.0_51]

Try switching to a newer Java 8. For example, the latest Java 8 from Zulu is at version 1.8.0_442

That's weird because I have the newest official Java 1.8.0_441 installed already.
Is there some path I need to set for Minecraft to run it with the newer version and not the old one?

Okay, I set the path to Java 8 in Curseforge directly but the error is still there

at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0_441]
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) ~[?:1.8.0_441]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) ~[?:1.8.0_441]
at java.lang.reflect.Method.invoke(Unknown Source) ~[?:1.8.0_441]
at net.minecraft.launchwrapper.Launch.launch(Launch.java:135) [launchwrapper-1.12.jar:?]
at net.minecraft.launchwrapper.Launch.main(Launch.java:28) [launchwrapper-1.12.jar:?]

Caused by: java.lang.NoClassDefFoundError: net/minecraft/client/Minecraft
at net.minecraft.client.main.Main.main(SourceFile:38) ~[Main.class:?]
... 6 more
Caused by: java.lang.ClassNotFoundException: net.minecraft.client.Minecraft
at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:191) ~[launchwrapper-1.12.jar:?]
at java.lang.ClassLoader.loadClass(Unknown Source) ~[?:1.8.0_441]
at java.lang.ClassLoader.loadClass(Unknown Source) ~[?:1.8.0_441]
at net.minecraft.client.main.Main.main(SourceFile:38) ~[Main.class:?]
... 6 more
Caused by: org.spongepowered.asm.mixin.transformer.throwables.ReEntrantTransformerError: Re-entrance error.
at org.spongepowered.asm.mixin.transformer.MixinProcessor.applyMixins(MixinProcessor.java:366) ~[!mixinbooter-10.6.jar:?]
at org.spongepowered.asm.mixin.transformer.MixinTransformer.transformClass(MixinTransformer.java:240) ~[!mixinbooter-10.6.jar:?]
at org.spongepowered.asm.mixin.transformer.MixinTransformer.transformClassBytes(MixinTransformer.java:208) ~[!mixinbooter-10.6.jar:?]
at org.spongepowered.asm.mixin.transformer.Proxy.transform(Proxy.java:71) ~[!mixinbooter-10.6.jar:?]
at net.minecraft.launchwrapper.LaunchClassLoader.runTransformers(LaunchClassLoader.java:279) ~[launchwrapper-1.12.jar:?]
at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:176) ~[launchwrapper-1.12.jar:?]
at java.lang.ClassLoader.loadClass(Unknown Source) ~[?:1.8.0_441]
at java.lang.ClassLoader.loadClass(Unknown Source) ~[?:1.8.0_441]
at net.minecraft.client.main.Main.main(SourceFile:38) ~[Main.class:?]
... 6 more

You didn't send your full error log, please paste the whole latest and debug.log in your logs folder

I have no debug.log but I can attach the latest log I have as of now.

latest.log

And you have Dumplicate UniversalTweaks and Xaeros_Minimap Jars

Try to Remove [MixinCompat-1.1-1.12.2] and _MixinBootstrap-1.1.0.jar

2025-04-08-6.log

I removed MixinCompat and Bootstrap + deleted the duplicates but no success.

Can you provide your modlist?

Is there a file / list where it is listed up or do I have to type everything myself?

Easiest way: run dir /S > mods.txt and remove any sensitive information from mods.txt and send it here.

Okay, and where do I run it? In cmd?

Yes, in your mods folder

The command isn't working. It says that the path C: \S isn't existing..

I can't help you much, you have to write the command out properly, make sure your cmd's in the mods directory.

I had a look at your latest.log and you have mods with different versions all running at once, which is terrible, this is not a MixinBooter issue, just ask for help in our discord instead.

Top right discord icon on our website: https://cleanroommc.com/

Thanks, just found it too.. xD