How to install Minecraft mods with Fabric

This guide walks you through setting up Fabric and getting my mods running – and what to do if Minecraft won't start afterwards. It works for any Fabric mod for Minecraft 1.21.1, including Wild Potions and ChronoShift.

What is Fabric?

Plain Minecraft Java Edition can't load mods. For that you need a mod loader – a small program that reads every mod from a specific folder when the game starts. Fabric is one of the most popular mod loaders because it's lightweight, supports new Minecraft versions quickly and barely slows the game down.

Fabric comes in two parts: the Fabric Loader, which you install once, and Fabric API, a toolkit that almost every Fabric mod depends on. Fabric API is a mod itself and simply goes into your mods folder.

What you need

  • Minecraft Java Edition on a computer (Windows, macOS or Linux) – Bedrock Edition, consoles and phones won't work
  • the official Minecraft Launcher, with Minecraft 1.21.1 started at least once
  • the Fabric Installer
  • Fabric API for 1.21.1
  • the mod you want to play, for example from this website

Make a backup first: Your worlds live in %appdata%\.minecraft\saves (Windows). Copy your world's folder somewhere else before opening it with mods for the first time. Mods don't normally break worlds – but better safe than sorry.

Installation in 5 steps

  1. Run the Fabric Installer: Download the Fabric Installer (there's an .exe for Windows, otherwise use the "Universal" .jar) and open it. Stay on the "Client" tab.
  2. Pick the version and install: Set "Minecraft Version" to 1.21.1, keep the newest loader version selected and leave "Create profile" ticked. Click "Install". After a few seconds the installer confirms that everything worked.
  3. Open the mods folder: On Windows press Windows + R, type %appdata%\.minecraft and press Enter. If there's no mods folder, create one.
    macOS: ~/Library/Application Support/minecraft/mods
    Linux: ~/.minecraft/mods
  4. Add the mods: Copy the downloaded mod file (it ends in .jar) and Fabric API into the mods folder. Don't unzip or double-click the files – just drop them in.
  5. Start with Fabric: Open the Minecraft Launcher, choose the "fabric-loader-1.21.1" profile next to "Play" and start the game. The bottom-left corner of the main menu now shows that Fabric is loaded.

Tip: The small mod "Mod Menu" adds a "Mods" button to the main menu that lists every installed mod, so you can instantly see whether a mod was loaded.

Verify your download: is my file genuine?

Mods are programs, so only download them from places you trust: straight from the developer, from CurseForge or from Modrinth. Sites that "mirror" other people's mods sometimes bundle ads or malware.

Every one of my mod pages lists a checksum (SHA-256). It's a fingerprint of the file: if even a single byte changes, the checksum looks completely different. Here's how to compare it:

  • Windows: Open PowerShell and type Get-FileHash "$env:USERPROFILE\Downloads\chronoshift-1.18.1.jar" (adjust the file name).
  • macOS: In Terminal, run shasum -a 256 ~/Downloads/chronoshift-1.18.1.jar
  • Linux: In a terminal, run sha256sum ~/Downloads/chronoshift-1.18.1.jar

If the string of letters and numbers matches the one on the mod page, your file is exactly the one I uploaded. By the way: it's normal for your browser to warn you when downloading a .jar file. It does that for every Java file, no matter who made it.

Common problems and fixes

Almost every startup error comes down to one of these.

Minecraft starts, but the mod isn't there

Usually the normal profile was started instead of "fabric-loader-1.21.1" – check the selection next to "Play". Is the file in the right mods folder? If you set a custom game directory in the launcher, it belongs in the mods folder there.

"Incompatible mods found" or a mod "requires fabric-api"

Fabric tells you exactly what's missing. "requires fabric-api" means Fabric API isn't in your mods folder. "requires minecraft 1.21.1" means you're launching a different Minecraft version. If a mod asks for a newer "fabricloader", just run the Fabric Installer again.

The game crashes on startup

Take every mod except Fabric API out of the folder and add them back one by one – that way you'll find the mod causing the crash. The details are in .minecraft\logs\latest.log and the crash-reports folder. Feel free to send me the file on Discord and I'll take a look.

I mixed Forge mods and Fabric mods

That doesn't work. Fabric only loads Fabric mods. Set up separate profiles for Forge and Fabric (see below) so the mods don't get in each other's way.

Two versions of the same mod in the folder

After an update the old file often sits next to the new one. Fabric won't load like that – delete the old version so there's only one file per mod.

Double-clicking the .jar does nothing or something odd

Mod files aren't opened or installed – they only go into the mods folder. If your computer renamed the file to .zip, change the ending back to .jar.

Updating or removing mods

To update, delete the old file from the mods folder and drop in the new one. To remove a mod, just delete its file. Careful: blocks and items from a removed mod disappear from your worlds – so only open an important world without the mod after making a backup.

Separate profiles for different modpacks

If you use several mod collections, give each one its own game directory: in the Minecraft Launcher, edit the Fabric profile under "Installations" and pick a new folder under "Game directory", for example %appdata%\.minecraft-fabric. Every directory then has its own mods folder and its own worlds.

Mods on a server

For your own server, download the Fabric server for 1.21.1 from fabricmc.net/use/server, start it once and accept the EULA in eula.txt. Then put the mods and Fabric API into the server's mods folder. Mods that add new blocks or items – like mine – are also needed by every player, in the same version as the server.

Still have questions? Join my Discord server or message me through the contact form.