Can I add mods after the server has started, or will it crash?

Dropping a mod into the folder while the server is running won't do what you'd hope — and can cause a crash on the next restart. Here's how mod loading actually works and how to add mods safely.

When mods load

Mods are loaded at startup, so adding a mod to the folder while the server runs does nothing until you restart. And if the new mod (or a missing dependency) is incompatible, it can crash on that restart.

The safe way to add mods

1. Stop the server first.
2. Add the mod to the mods folder (via the Mods & Plugins page, Files, or SFTP).
3. Match versions — the mod must fit your loader and MC version.
4. Keep a backup (Back up now on the Backups page) so you can roll back.
5. Start and watch the Console.

Warning: Always add mods with the server stopped and matching versions — a mismatched mod or missing dependency can crash the restart.

Frequently asked questions

Can I add a mod without restarting? No — mods only load at startup, so nothing happens until you restart.

Why did adding a mod crash my server? The new mod, or a missing dependency, was incompatible. Match versions and check dependencies, and keep a backup to roll back.