Corrupted files

Startup Crash: ClassNotFoundException: org.objectweb.asm.ClassVisitor

What it looks like in the log

java.lang.ClassNotFoundException: org.objectweb.asm.ClassVisitor

How to fix it

  1. If you use a third-party launcher like HMCL, open the launcher's download settings and switch the download mirror to Official (or another working mirror) to avoid pulling corrupted files.
  2. Delete the corrupted ASM libraries by using your launcher's 'Delete libraries' / 'Clear cache' management option, or manually delete the .minecraft/libraries/org/ow2/asm/ folder.
  3. Start the game while connected to the internet so the launcher re-downloads and verifies clean copies of the missing library files.
  4. If the error persists, delete the affected game version profile and reinstall Fabric, Forge, or OptiFine directly through your launcher's built-in automatic installer instead of a standalone installer.
LoadersForge, Neoforge, Fabric, Quilt, Vanilla
SeverityStops the game
CategoryCorrupted files

Check your own log

Related errors

Corrupted filesCorrupted Config File (NightConfig ParsingException: Not enough data available)Find the line starting with 'ConfigLoadingException: Failed loading config file' near the top of your crash reCorrupted filesCorrupted Mod Config File (NightConfig ParsingException: Invalid character)Find the line in your crash report starting with `Failed loading config file` to see the exact `.toml` filenamCorrupted filesFabric Error Remapping Game Jars (client-intermediary.jar.tmp)Close Minecraft and your launcher completely, open your instance or `.minecraft` folder, and delete the hiddenCorrupted filesJsonSyntaxException: Expected BEGIN_OBJECT but was STRING (Corrupted JSON File)Check the stack trace lines directly beneath 'Caused by: com.google.gson.JsonSyntaxException' in your log to sCorrupted filesMissing or Corrupted ASM Tree Library (org/objectweb/asm/tree/ClassNode)In your launcher settings (such as HMCL, PCL, or Prism Launcher), switch the download source from third-party Corrupted filesTotem Counter Crash: ExperimentalConfig.isDisableArmorStands() is NullClose Minecraft and open your game directory's `config` folder.