How to Use the Startup Tab and Change Your Server Version

The Startup tab controls exactly how your server process launches — which version runs, the startup command, and any environment variables the software needs.

What You'll Find There

• Startup command — the actual command line used to launch your server (usually pre-filled correctly by the egg and not something you need to touch).
• Docker image — which runtime environment it launches in (matters most for Java version on Minecraft — different Minecraft versions need different Java versions, and the image controls that).
• Variables — a form-based set of fields specific to whatever software you're running: version number, memory flags, game-specific settings like RCON passwords or map names.

Changing Your Server's Version

1. Open the Startup tab.
2. Find the version variable (labelled differently depending on the egg — often "Minecraft Version," "Server Jar Version," or similar).
3. Pick the version you want from the dropdown, or type it in if it's a free-text field.
4. Save changes, then restart the server — version changes only take effect on the next boot, since the correct jar/binary gets downloaded or switched during startup.

Java Version Matters on Minecraft

If you're jumping to a newer Minecraft version (or an older one), check whether it needs a different Java runtime — the Docker image selector on this tab is what controls that. Running a version that needs Java 21 on an image that only provides Java 17 (or vice versa) is one of the most common reasons a server fails to start after a version change.

Switching Server Software

Changing from Paper to Purpur, or Vanilla to Forge, isn't just a Startup tab edit — that's a full software swap best done through the Egg/Game Changer (see our egg changer guide), which handles installing the new software cleanly. The Startup tab is for changing which version of the same software you're already running.

If a Version Change Breaks Startup

• Check the console immediately after restarting — the exact error (missing Java version, incompatible plugin, corrupted download) is almost always shown there.
• If a plugin/mod isn't compatible with the new version yet, that's usually the actual cause of a post-update crash, not the version change itself — check your plugin list against the new version's compatibility before assuming something's wrong on our end.
• You can always roll back to the previous version the same way you changed it, and restore a pre-update backup if files got modified in the process.

This tab looks intimidating at first glance because of all the variables, but 90% of the time the only field you'll ever touch is the version selector.