Install Supplementaries on a Minecraft server

Supplementaries, by MehVahdJukaar and Plantkillable, adds many small "Vanilla+" blocks and items: jars, signposts, faucets, weather vanes, spring launchers, sconces, planters, lights, decoration and automation pieces. It runs on Fabric, Forge and NeoForge and needs a library mod called Moonlight Lib. This guide installs it on a NeoForge server and notes what changes on Fabric and Forge.

Checked against Supplementaries 1.21.1-4.0.2 on NeoForge 1.21.1, October 2026.

Pick the right build

Modrinth lists these newest files:

• NeoForge or Fabric, Minecraft 1.21.1: Supplementaries 1.21.1-4.0.2.
• Forge or Fabric, Minecraft 1.20.1: Supplementaries 1.20-3.1.44.
• Older versions: builds for Minecraft 1.19.x and 1.18.2 are also published, last updated in 2024 or earlier.

To change loader or version, open JAR Manager under More, choose the loader under Server software and the version under Minecraft version, then press Apply change. The panel picks the Java version for you. Switching reinstalls the server and keeps your world, so make a backup in the Backups tab first. Change your Minecraft version or mod loader has the full steps.

Install it

1. Open Mods under Content and keep the Modrinth chip selected. The Game version filter starts on your server's version.
2. Search for Supplementaries and press Install on Supplementaries. Other results, such as Supplementaries Squared and Supplementaries Compat, are separate projects.
3. A prompt titled "Needs 1 more add-on" names Moonlight Lib, which Modrinth lists as required. Press Install all.
4. Restart from the Console tab. The install toast says "Restart the server to load them".

On Fabric, the mod's metadata also requires Fabric API, and Modrinth's own dependency list for the 1.21.1 file does not name it, so the prompt will not offer it. Search for Fabric API and install it the same way before you restart.

Open the Installed view to check. Supplementaries and Moonlight Lib should both be listed with no Failed to load badge.

Players need it too

Modrinth lists Supplementaries as required on both the client and the server, so each player installs the same version for their loader and Minecraft version, plus Moonlight Lib (and Fabric API on Fabric). Join a modded server from your launcher covers the player side, and Fix the mismatched mod channel list error explains a refusal when versions differ.

Settings

The project's wiki says almost every feature can be switched off in the config. It describes a common config, which holds most of the mod's logic and some optional features that are off by default, such as colored blackboards and XP bottling, and a client config for visuals. The wiki names the files supplementaries-common.toml and supplementaries-client.toml. On NeoForge 1.21.1, supplementaries-common.toml sits in your config folder after the first start on a server, and no client file is written there. Open it in the File Manager. Stop the server before you edit a file there, and restart afterwards.

Blocks and items can also be changed with datapacks and resource packs. The wiki's Customization page explains how.

Common problems

• The server stops at startup: Moonlight Lib is missing or older than the version Supplementaries asks for (3.6.4 for the 1.21.1 build). Install the newest Moonlight Lib for your loader and Minecraft version, and on Fabric install Fabric API.
• No results for your version: Modrinth lists builds up to Minecraft 1.21.1. Change the version in JAR Manager.
• Other crashes: Fix mod and plugin errors on Minecraft covers reading the Console log.