Choosing a Java Runtime for a Minecraft Anticheat Server

Which Java runtime should an anticheat server use?

Use the Java runtime that your server software documents for the Minecraft version you run. Then check the anticheat and PacketEvents release notes for their own minimums, and follow the higher one. Finally, confirm that your start script or panel template launches that exact runtime, because the Java on your PATH is not always the one a service uses.

Find each documented minimum

Each component may publish its own requirement. Read the current documentation for each one and write the value down with its source link and the date you checked. Do not copy a minimum from an old forum thread.

• The server software, such as Paper, Spigot, Purpur, or Folia, from its official documentation.
• The anticheat, from its release notes or documentation for the exact build you will install.
• PacketEvents, from its official release page for the version the anticheat expects.
• Any other plugin that loads at the same time, especially one that hooks into packets or combat.
• The host image or container, from the host's own documentation.

Check which Java the start script actually runs

Run these commands as the same user that starts the server. Compare their output with the runtime path in your start script, service file, or panel template. A mismatch here is one of the most common reasons a correct install behaves like a broken one.

java -version
which java
readlink -f "$(which java)"

How do the components compare?

Keep one row per component. The point of the table is to find the strictest requirement and the source you used to set it.

Does a Minecraft upgrade change the runtime requirement?

It can. A new Minecraft version can change the server software's documented runtime, and a plugin update can raise its own minimum. Treat the runtime as part of the upgrade, not a separate step. Check the new requirement before you replace any jar, and test the new runtime in staging with the full plugin set.

For version change planning, see the staging checklist for Minecraft version updates.

What does a runtime mismatch look like in the log?

A plugin built for a newer runtime can fail to load on an older one with a class-version error. A runtime that does not match the start script can also leave you with a server that behaves differently after a restart. Save the log first, then compare the runtime path in the log's startup lines with the path you expected.

• A class-version error on load points to a runtime older than the build requires.
• The server starts from SSH but fails from the panel, which often means a different runtime path.
• Two Java installs exist, and an update changed the default that the service uses.
• The version in the log differs from java -version run as the service user.

How do you change the runtime safely?

Change one thing at a time. Record the current runtime, make the change on a staging copy, start the server, and check the startup log. Only after the staging run is clean should you change production, and keep the old runtime path so you can roll back in one edit.

Who owns the runtime decision?

One person should own the runtime choice and its record, even on a team. When an anticheat, a plugin, and the host each have a separate runtime setting, the most recent change can silently win. Name the owner in the change log and require that owner to sign off on any runtime change, including changes made by a host.