Minecraft 1.21.3 with Fabric

October 17, 20261 minEntity

Entityprism launcher 1.21.3 fabric1.21.3 fabricprism launcher

Create a Prism instance for Minecraft 1.21.3 on Fabric. Use Java 21.

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Minecraft: 1.21.3
Loader: Fabric
Java: Java 21

1.21.3 + Fabric

Add Instance → 1.21.3 → install Fabric. Assign Java 21 under Settings → Java.

This pairing existed for that version. Older versions are not given NeoForge or Quilt pages.

Installer: /download.

Prism Launcher screenshot showing the mod updating user-interface — Check for and apply mod updates for a whole instance at once.

Frequently asked questions

Which Java for 1.21.3?

Java 21. Mismatch is a common exit code 1.

Overview

Prism Launcher Mod Loaders

Install or switch Fabric, NeoForge, Forge, Quilt, or LiteLoader on any Minecraft instance in two clicks without manual JAR installers.

Overview

Prism Launcher Java & JVM Configuration

Match the exact Java runtime (Java 21, Java 17, or Java 8) to your Minecraft version, tune min/max RAM, and pass GC JVM arguments.

Entity

Fabric Loader in Prism Launcher

Lightweight, modular mod loader that updates within hours of new Minecraft releases and powers the modern Sodium/Iris performance stack. Supports Minecraft 1.14 – 1.21.4+ (plus snapshots).

How-to

How to Set Up Fabric Loader in Prism Launcher

Complete setup checklist for Fabric Loader on Windows: version selection, Fabric API (fabric-api.jar), and shader/mod installation.

Entity

NeoForge in Prism Launcher

The modern community-driven successor to Minecraft Forge for 1.20.4 and 1.21+, supported natively in Prism Launcher's Version tab. Supports Minecraft 1.20.1 – 1.21.4+.

Get Prism Launcher

Windows, macOS & Linux

Free and open source. Sign in with the Microsoft account that owns Minecraft, then create your first instance.

Download More Loaders guides

Prism Launcher on Windows showing several modpacks and instances