Minecraft Server Java Version: Which One You Need
Minecraft 1.18 to 1.20.4 needs Java 17, 1.20.5 to 1.21.x needs Java 21, 26.1 and newer needs Java 25, and anything up to 1.16.5 needs Java 8.
2 min read · Updated Oct 24, 2026 · By GuavaHost Team
The Java version your Minecraft server needs depends only on the Minecraft version it runs:
- Minecraft 1.8 to 1.16.5 → Java 8 (1.16.5 also runs on Java 11)
- Minecraft 1.17 and 1.17.1 → Java 16 (Java 17 also works)
- Minecraft 1.18 to 1.20.4 → Java 17
- Minecraft 1.20.5 to 1.21.x → Java 21
- Minecraft 26.1 and newer → Java 25
On a GuavaHost server you do not normally pick this yourself: the Version page installs the matching Java with the version, and the rest of this guide covers how it does that, when to change it by hand, and what the errors look like when it is wrong.
A Minecraft version will not start on a Java older than the one listed for it. Starting with its first release of 2026, Mojang uses year-based version numbers, so the release after the 1.21 updates is 26.1 rather than 1.22. If a future release needs a newer Java than this list shows, the startup error tells you which version it wants.
A server on the wrong Java version usually fails to start with one of these:
Unsupported Java detected
Java version is too old
Unsupported class file major version
Modded servers follow the same table
If you're using modded servers like Forge, Fabric, or Paper, the required Java version usually follows the same Minecraft version requirements. The main exception is older modded servers: Forge on 1.12.2 and many older modpacks only run on Java 8, so do not move them to a newer Java.
The Version page picks Java for you
When you install a Minecraft version from the Version page (under Minecraft tools in your server menu), the panel checks which Java that version needs. If your server is on an older Java than that, it moves the server up to a matching one before installing. It never moves you down, so a server that already runs fine is left alone. How to change your Minecraft Java server version walks through the Version page.
That covers most servers. It does not cover two cases:
- Minecraft 26.1 and newer, which need Java 25.
- Older modded servers that need Java 8, such as Forge on 1.12.2, when the server is currently on a newer Java.
Choosing Java by hand (classic game panel)
Picking a Java version yourself is not part of your control panel at customer.guavahost.com. It is still available in the classic game panel at panel.guavahost.com, which you sign in to with the same GuavaHost account (see Using the classic game panel).
- Stop your server.
- In the classic game panel, open your server and go to the Startup tab.
- Find the Docker Image setting and select the Java version from the list above.
- The change saves automatically. Start your server again.
If your server still won't start or you're unsure which Java version to use, please contact our support and we'll help you get it running.
- minecraft
- java
- java-version
- startup
- docker-image
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