Your hosted server’s Java runtime is separate from Minecraft’s game version and the Java installed on your computer.
Choose the required Java version
Minecraft 1.20.5 through 1.21.11 requires Java 21. Minecraft 26.1 requires Java 25. Older games and modpacks can need older Java, so check the exact software or pack requirements.
References: Minecraft 1.20.5, Minecraft 26.1 and Paper Java requirements.
Change the runtime
- Open Startup and choose the required Java version in Docker Image.
- If the required version is not listed or the field is locked, contact Konnect support to change it.
- Restart the server. Check the Java runtime and complete startup in Console, then join with the correct game or pack release.
The Paper, Fabric and NeoForge eggs list supported Java images. Available choices depend on your server type.
If startup fails
UnsupportedClassVersionError usually means the named file needs a newer Java runtime. A mod or plugin can require newer Java than the base server. Unable to access jarfile instead points to a missing or incorrect launch file. Keep Forge or NeoForge’s required argument file format.
Further help: Paper startup troubleshooting.
Related: Change Minecraft version · Install a modpack · Minecraft hosting.
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