Fix "ZIP END header not found" jar errors

A jar is a zip file that can carry a Java manifest in its META-INF folder. When Java cannot read one, the server stops with an error that names the zip format, not your plugin or your server software. The message is blunt, but it narrows the problem to a single file that is missing, empty or cut short. This guide shows how to tell which file, and how to replace it.

Checked against the OpenJDK 25 launcher and zip code and Minecraft 26.3, October 2026.

What the messages mean

The first two can come from any jar the server loads, including a plugin or a mod. The last two come from the file Java starts first, which is server.jar on Paper, Purpur, Folia and Vanilla, fabric-server-launch.jar on Fabric and quilt-server-launch.jar on Quilt. On Forge and NeoForge it is a forge- jar on older versions, or an arguments file under libraries on newer ones.

Work out which file it is

1. Open the Console tab and find the first error after you pressed Start.
2. Look at the lines around it for a file name ending in .jar. If the name is server.jar, go to the next section.
3. If the error appears after the server software has started loading, open Plugins (or Mods on Fabric, Forge, NeoForge and Quilt) and click Installed. On Paper, a Failed to load badge marks the add-on the log complained about. If there is no badge, use the file name in the log line. Go to the section after next.

If server.jar is the problem

Run the installer again, which downloads the server jar again. Make a backup first, as in Create and restore backups.

1. Open Settings under More and scroll to Danger zone.
2. Click Reinstall under Reinstall server and confirm.
3. Watch the Console. The installer prints the jar's name and size when the download finishes. Then click Start.

If you just changed software or version in the JAR Manager and the new jar is the damaged one, there may be a Previous jar kept. card. Stop the server and click Restore previous jar to go back.

If a plugin or mod is the problem

1. In Installed, click the trash button on the broken add-on and confirm Delete. You can also delete the file from the plugins or mods folder in the File Manager.
2. Find it in the Store and click Install again. Where the source publishes a checksum (Modrinth and CurseForge give a sha1, Hangar and GitHub a sha256), the panel compares the download with it and deletes the file if they differ.
3. Click Restart on the Console tab.

If you uploaded the file yourself, upload it again. When it finishes, compare its Size in the File Manager with the file on your computer. A browser upload is capped at 100 MB per file, and larger files should go over SFTP, as in Connect over SFTP with FileZilla or WinSCP.

Stop it happening again

• Let an upload finish before you restart the server.
• Prefer the Store for add-ons. Where the source publishes a checksum, a damaged download is deleted instead of kept.
• Take a backup before you change software, version or add-ons.

If the same error returns after a clean reinstall, download the log with Download Log on the Console tab and send it through Contact support and open a ticket. For the other start-up messages, Fix a Minecraft server that will not start is the place to start.