warningLauncher ErrorsAffects: All versions
How to Fix MultiMC/Prism Instance Launch Error
Fix MultiMC/Prism Instance Launch Error by configuring the correct Java path and re-downloading instance libraries.
Quick Fix
Go to Settings > Java and set the correct Java installation path. Ensure it matches the Minecraft version requirements.
Error Message
Error: Instance X failed to start / Could not set up instanceHow to Fix
1
Open Settings > Java and set the correct Java path
2
Ensure Java 21 for Minecraft 1.21+
3
Re-download instance libraries: right-click instance > Edit > Libraries > Redownload
4
Check the instance log for specific errors
Common Causes
- Java path not configured in MultiMC/Prism settings
- Instance configured for wrong Java version
- Missing libraries for the instance
Diagnostic Steps
- Open launcher settings
- Set Java path correctly
- Check instance version requirements
- Re-download libraries if needed
FAQ
Where does MultiMC/Prism store Java settings?
Global settings are in Settings > Java. Per-instance settings override global ones in Edit Instance > Settings > Java.