How to Use CoroUtil on a Multiplayer Server Without Breaking It

CoroUtil is not a client-only cosmetic library — it provides shared code that dependent mods use on both sides. That means server setup matters, and getting it wrong causes disconnects, registry errors, or features that silently do nothing for players.

Server-Side Requirements

Install CoroUtil on the server in the same mods folder as the mods that depend on it, using the same loader and Minecraft version. If the dependent mod is required on the server, so is CoroUtil. A server missing CoroUtil will usually refuse to start or will crash when a dependent mod initializes.

Client-Side Requirements

In most cases, players connecting to the server also need CoroUtil installed, because the dependent mods register content or send packets that the client must understand. If a player joins without it, expect a disconnect with a mod-list or registry mismatch message.

Keeping Versions in Sync

The server and all clients should run the same CoroUtil build and the same versions of the dependent mods. A client on a newer or older build than the server is a frequent cause of "incompatible mods" kicks.

Practical Checklist

1. Confirm the server's CoroUtil matches the server's dependent mods.

2. Confirm every client's CoroUtil matches the server's.

3. Confirm no one has a duplicate or wrong-loader CoroUtil file.

4. After any mod update, update CoroUtil on both server and clients together.

If a dependent mod's feature works in singleplayer but not on your server, a CoroUtil mismatch between client and server is the first thing to check.