Which Java Version for a Minecraft Server? 26.3 Needs Java 25

Short answer: Minecraft 26.1, 26.2 and 26.3 need Java 25. Versions 1.20.5 to 1.21.11 need Java 21, 1.18 to 1.20.4 need Java 17, 1.17 needs Java 16, and everything from 1.7.2 to 1.16.5 runs on Java 8. These numbers come from Mojang: every Minecraft release states the Java version it was built for. Start a server on a Java that is too old and it stops right away, usually with an UnsupportedClassVersionError (Paper shows its own message first).

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Java per Minecraft version

The Java column is the javaVersion that Mojang lists for each release in its version manifest; we checked all releases from 1.7.2 to 26.3 on 19 October 2026. The requirement comes from Minecraft itself, so it is the same for Vanilla, Paper, Fabric, Forge and NeoForge.

Paper's own advice differs for older versions

Paper publishes a recommended Java per version that is a little stricter than Mojang for older releases:

• 1.7.10 to 1.11: Java 8
• 1.12 to 1.16.4: Java 11 (Mojang: 8)
• 1.16.5: Java 16 (Mojang: 8)
• 1.17 to 1.19: Java 17 (Mojang: 16 for 1.17)
• 1.20 to 1.21.11: Java 21 (Mojang: 17 up to 1.20.4)
• 26.1 and newer: Java 25

For 26.x both agree. Paper 26.3 checks the Java version before it starts and stops with this message when it is too old: "Minecraft 26.1 and newer requires running the server with Java 25 or above." On a Paper server you can follow Paper's list; on Vanilla and modded servers, use the Mojang column.

Why 26.1 moved to Java 25

Minecraft 26.1 came out on 24 March 2026 as the first release with the year-based numbering: version numbers in 2026 begin with 26. Its release notes say it plainly: "The game now requires Java 25". Players barely notice, because the Minecraft Launcher brings its own Java (since 26.1 the Microsoft build of OpenJDK 25). A server gets no such help. Whoever runs it picks the Java, so an update from 1.21.x to 26.x always means changing Java as well.

The error you see when Java is too old

The console stops with a line like this one (Minecraft 26.3 started on Java 21):

java.lang.UnsupportedClassVersionError: net/minecraft/bundler/Main has been compiled by a more recent version of the Java Runtime (class file version 69.0), this version of the Java Runtime only recognizes class file versions up to 65.0

The two numbers tell you everything. The first is the Java the server needs, the second is the Java that is running: 69 is Java 25, 65 is Java 21, 61 is Java 17, 60 is Java 16 and 52 is Java 8. "Version 69.0, up to 65.0" therefore means: Java 25 is needed, Java 21 is installed.

Changing Java in the HostValues game panel

1. Open your server in the game panel and go to the Startup tab.
2. Under Docker Image, choose the Java that matches your Minecraft version from the table, for example Java 25 for 26.3 or Java 21 for a 1.21.1 modpack.
3. Restart the server from the Console tab and read the first lines of the log.

The panel does not change Java for you. When you switch to another Minecraft version or server software in the Versions tab, check the Docker Image under Startup straight after. The Minecraft images in the panel cover Java 8, 11, 16, 17, 18, 19, 20, 21, 22, 25 and 26 (October 2026).

Running a server on your own PC

On your own machine you install Java yourself. For 26.x that means a Java 25 JDK, for example Eclipse Temurin 25 from Adoptium, which has an installer for Windows. Then run java -version in a terminal: according to the Paper documentation the output should start with openjdk 25 and contain 64-Bit in the last line. The long-term support (LTS) releases at Adoptium are Java 8, 11, 17, 21 and 25. Java 26 and 27 also exist, but they are not LTS releases.

Modpacks: the pack's Minecraft version decides

A modpack is built for one Minecraft version and one loader, so look up the version on the pack page and take the Java from the table. All the Mods 10 is on 1.21.1 (NeoForge) and needs Java 21. All the Mods 11 is on 26.1.2 and needs Java 25. Prominence II: Hasturian Era runs on 1.20.1 with Fabric and Better MC on 1.20.1 with Forge, both Java 17. RLCraft stays on 1.12.2, which means Java 8. Our overview of the best modpacks for a server lists version, loader and Java for ten popular packs.

Which Java do I need for Minecraft 26.2?

Java 25. Mojang lists Java 25 for every 2026 release: 26.1, 26.1.1, 26.1.2, 26.2 and 26.3.

Can I run a 26.3 server on Java 26?

Paper only requires Java 25 or newer, so Java 26 meets the minimum. Java 25 is the version Mojang ships with the launcher and it is an LTS release, which makes it the safe choice for a server.

Is the newest Java always fine for older versions?

Not always. Paper itself recommends a newer Java than Mojang for several older versions (see above), so a newer Java often works there. Mods are less predictable: if an older modpack does not start on a newer Java, switch back to the Java that belongs to its Minecraft version.

My server does not start after updating to 26.3. What now?

Check the Docker Image under Startup first: after an update from 1.21.x it is often still on Java 21. Set it to Java 25 and restart. Still failing? Look in the console for the first line with "Error" or "Exception" and send it along in a support ticket.

Does changing Java affect my world?

No. Java is only the runtime that starts the server; your world files stay the same. Changing the Minecraft version is different, because a world that has been opened in a newer version cannot simply go back. Make a backup in the Backups tab before you update.

On every Minecraft plan at HostValues you choose the server version in the Versions tab and the Java image under Startup, per server. For an update to 26.3, see the Paper 26.3 server guide.