Client, server and both environments
A client-only project changes what an individual player sees or controls and usually belongs only in that player's mods folder. Server-only projects change dedicated-server behavior without requiring every player to install them. Many gameplay and content mods must be installed on both sides with matching versions.
Do not decide from the project name alone. Performance, map and utility mods can target different environments. Check the environment label and installation section for the exact file.
Find the mod named by the dedicated server
Fabric may explicitly say a mod cannot be loaded in the dedicated server environment. Other loaders can fail when the mod references Minecraft client, rendering or screen classes. Start with the first environment or class-loading failure rather than later shutdown messages.
Remove the named client-only JAR from the server's mods directory, not from player clients. If the project includes a separate server component, follow its documentation instead of copying the client file.
Keep the server and clients compatible
Removing a truly client-only mod from the server should not require removing it from clients. Mods that add registered blocks, items, entities or network messages are more likely to require both sides, and a mismatched set can prevent players from connecting.
Keep a documented server mod list for the pack. When updating, compare environment requirements before synchronizing the entire client mods folder to the server.
Quick troubleshooting checklist
- ✓Read the first environment error
- ✓Confirm the project's environment label
- ✓Remove client-only JARs from the server
- ✓Keep supported client copies
- ✓Match versions for mods required on both sides
- ✓Maintain a separate server mod list
Every launch creates a new result. After making one change, use the newly generated latest.log rather than continuing from an older report.