Fix Valheim Mod Joins: Client-Side Mods Explained

Prove the client/server boundary

1. 1
   Step 1: Read the mod page and label the mod client-only, server-side, or client-required; write down the loader, version, dependency, and configuration owner.
2. 2
   Step 2: Launch a vanilla client against the server, then add the smallest supported mod set and repeat the same join test with the same world.
3. 3
   Step 3: Compare the two results, keep the working profile, and remove client-required plugins from the crossplay test when the target platform cannot use them.
4. 4
   Step 4: Launch once, inspect the log and expected plugin/config path, then stop if the clean profile no longer loads.

Client-side and server-side mods create different responsibilities. A player can have a mod that never reaches the server, while a required client plugin can prevent another platform from joining at all.

• Label each mod by loader, version, dependency, and whether every player needs it.
• Run a vanilla join test before adding the smallest supported mod set.
• Keep the crossplay test clean when the target platform cannot run a client-required plugin.

Roll back before touching the main save

• Remove client-required plugins from the crossplay test.
• Compare a vanilla client and server before changing five configs.
• Restore the last known-good mod list when the save fails to load.

Test the next mod safely

• mod installation guide
• crossplay guide
• npc mod guide
• attack animation mod guide