Fabric Snapshot 21w39a Server Jar Download

Experimental — snapshot Official source

The Fabric server launcher for Minecraft Snapshot 21w39a uses Fabric Loader 0.20.1 and installer 1.1.2; on first start it downloads the vanilla Snapshot 21w39a server from Mojang. It requires Java 16 or newer.

Download

Download Fabric server launcher178 KB

Downloads from meta.fabricmc.net — Official — FabricMC.

The upstream does not publish a checksum for this file. MCJarHub computes a SHA-256 for such files on a schedule and shows it here once available — see how we source & verify.

Source: Official — FabricMC No checksum published yet Last checked: Report a problem

Version facts

Minecraft release date
ChannelPreview (weekly)
Required JavaJava 16 or newer · Temurin 16
Fabric Loader0.20.1
Fabric installer1.1.2
Fabric API (mod)0.40.6+1.18
File size178 KB
LicenceApache-2.0
Upstream projectfabricmc.net

What changed

Fabric Loader 0.20.1 release notes What's new in Minecraft Snapshot 21w39a (Minecraft Wiki)

Compatibility

Loads Fabric mods for Minecraft Snapshot 21w39a; most need Fabric API 0.40.6+1.18 in the mods/ folder.

Players need a Minecraft: Java Edition Snapshot 21w39a client on the same version.

Minecraft Snapshot 21w39a in other server software

Snapshot Quilt

Known issues & safety notes

  • Preview builds are experimental: they can corrupt or irreversibly upgrade worlds, and most plugins and mods do not support them yet. Test on a copy of your world.
  • Known issues: search Fabric's issue tracker for 21w39a

How to set up Fabric Snapshot 21w39a

  1. Install Java 16 or newer (e.g. Eclipse Temurin) and check it with java -version.
  2. Download the Fabric server launcher above (about 178 KB) into an empty folder.
  3. Start it with the script below. On the first start the launcher downloads the vanilla Snapshot 21w39a server from Mojang and the Fabric libraries — this needs internet access.
  4. Accept Mojang's EULA in eula.txt (eula=true) and start again.
  5. Put mods into mods/. Most mods need Fabric API 0.40.6+1.18 there too.

Linux / macOS — start.sh

#!/bin/sh
# start.sh — Fabric 21w39a
cd "$(dirname "$0")"
JAVA_MAJOR=$(java -version 2>&1 | awk -F'"' '/version/ {split($2, v, "."); print (v[1] == "1") ? v[2] : v[1]}')
if [ "$JAVA_MAJOR" -lt 16 ] 2>/dev/null; then
  echo "Java 16 or newer is required (found Java $JAVA_MAJOR)."
  exit 1
fi
java -Xms6G -Xmx6G -jar fabric-server-mc.21w39a-loader.0.20.1-launcher.1.1.2.jar nogui

Windows — start.bat

@echo off
REM start.bat — Fabric 21w39a
REM Needs Java 16 or newer: run "java -version" to check.
java -Xms6G -Xmx6G -jar fabric-server-mc.21w39a-loader.0.20.1-launcher.1.1.2.jar nogui
pause

Modded servers need more memory: 6–8 GB for a light modpack, 8–12 GB or more for large packs. Leave 1–1.5 GB for the operating system. How much RAM?

Docker

docker run -d -p 25565:25565 -e EULA=TRUE -e TYPE=FABRIC -e VERSION=21w39a --name mc itzg/minecraft-server

Uses the community itzg/minecraft-server image, which downloads the file itself.

Upgrading

FAQ

What Java version does Fabric Snapshot 21w39a need?

Fabric Snapshot 21w39a needs Java 16 or newer. Running it on an older Java fails with an UnsupportedClassVersionError mentioning class file version 60.0.

Is Fabric Snapshot 21w39a safe for my survival world?

Only on a copy. Preview versions are experimental and upgrade worlds irreversibly; keep a backup and don't switch a live world to a snapshot, pre-release or release candidate.

Why is the Fabric server file so small?

It is only a launcher. On the first start it downloads the vanilla Minecraft Snapshot 21w39a server from Mojang and the Fabric Loader libraries.