How do I set the startup jar/script and fix "invalid or corrupt jarfile" errors?
Your server launches whatever file the Startup tab points to. When you see "invalid or corrupt jarfile," it almost always means that target file is either the wrong name or was damaged during upload. Here's how to point your startup at the right file and clear the error.
Why this happens
The Startup tab holds a variable that names the exact jar/file the server runs at boot. If that name is wrong, or the file itself is incomplete (a half-finished upload) or empty, the server can't launch it.
Fixing the startup file
- Open the Startup tab and check the server jar/file variable points to the correct filename.
- Switch to Files and confirm that file actually exists and isn't 0 bytes or a partial upload.
- Re-upload the jar if it's corrupt, or for Minecraft reselect the correct software via the Versions tab.
- Restart from the Console tab.
Warning: "Invalid or corrupt jarfile" nearly always means an incomplete upload or a wrong filename. Re-upload over SFTP and double-check the exact name in the Startup tab.
Tips & best practices
- For Minecraft, prefer the Versions tab over manual jar uploads — it installs the right file and sets your startup for you automatically.
- Upload large jars over SFTP rather than the browser for a more reliable transfer.
Frequently asked questions
The jar name has spaces or a typo — does that matter? Yes. Match the Startup variable to the exact filename, character for character.
Where do I set RAM? Also in the Startup tab — see our performance articles for the details.