Startup and Java version
How to choose Java and adjust the variables used to start the server.
The Startup menu controls the environment and parameters used to run the server. Incorrect changes can prevent startup; create a backup and record previous values before saving.
Startup command
The displayed command combines the Java executable, memory limits, time zone, and main server file. Under normal conditions, you do not need to edit it directly.
Do not remove memory limits defined by the platform. They protect the server and keep usage within the resources included in your plan.
Runtime image and Java
The runtime image selector determines the Java version available to the server. Use the version recommended for your software and Minecraft release:
- modern releases usually require newer Java;
- older servers may depend on previous versions;
- modpacks may list a specific Java requirement.
If the console reports an incompatible class or unsupported Java version, check this selection before changing plugins or mods.
Main variables
| Variable | Purpose |
|---|---|
| Minecraft Version | Game version to install or update |
| Server JAR File | Name of the .jar file executed at startup |
| Build Number | Specific software build; latest uses the newest available build |
| Custom Startup Flags | Advanced additional parameters for the JVM or server |
Some variable names may remain in English regardless of the selected panel language.
Changing versions safely
- Create a full backup.
- Stop the server.
- Confirm world, plugin, and mod compatibility.
- Change the Minecraft version, build, or required Java version.
- Start the server and watch the entire process in the console.
Do not downgrade a world unless the software explicitly supports it. Opening a world in an older version can remove blocks, entities, or data.
Custom flags
Use custom flags only when you understand the issue they address. Do not copy generic flag lists without checking the Java version, available memory, and server software. Incompatible flags can reduce performance or prevent startup.