Test client-only and server-only mods before distributing a pack

Why side separation matters

A client-only visual or interface mod can crash a dedicated server if it references client classes during startup. A server-only management mod may be unnecessary on every player computer. Required-on-both content must remain synchronized so registries, networking, and gameplay behavior agree.

Project pages often provide side metadata, but documentation can be incomplete. Use it as a starting point and verify in a disposable dedicated-server test.

Use a real dedicated server test

Single-player includes both client and integrated-server code, so it cannot reveal every dedicated-server problem. Start the actual server loader without graphical client components and inspect startup logs before connecting.

Then join with a clean client. Test more than login: place content blocks, open menus, travel, use commands, die, respawn, and reconnect. Network errors may appear only when a feature is used.

Document optional client features

Performance, map, shader, cosmetic, and interface projects may be optional for players. Keep them in a separate recommended list unless the server explicitly requires them. This reduces download size and makes troubleshooting easier.

When publishing a pack, label files clearly and avoid implying that server administrators should copy the entire client mods folder.

How to know you are finished

For test client-only and server-only mods before distributing a pack, the work is not finished when a file is merely downloaded. Treat it as finished when you can point to the setup you changed, explain why it matches the intended Minecraft version or platform, and repeat the result in a clean test or copied world.

Use the checklist as the exit test: clean client and server instances exist, every project has a side classification, dedicated server starts independently. If one of those checks is still uncertain, stop and verify that detail before moving to a main world, public server, or shared pack.

If the first failure you hit is "undefined", start with this fix: undefined This keeps recovery tied to the guide instead of turning into unrelated guesswork.