Solve Server vs Client Mod Crashes
Solve why your server crashes immediately after uploading a modpack or specific mods (missing class or renderer errors).
Advanced6 min
1. Understand Server vs Client-side Mods
Certain mods (e.g. Minimaps, Shaders, NEI/JEI, performance mods like Sodium/Lithium/Iris, or cosmetic mods) belong only on the player's computer (Client-side). Putting them in the server's 'mods' folder crashes the server instantly.
2. Identify the error in the crash log
Open 'logs/latest.log' and search for errors related to graphics, renderers, or client classes.
java.lang.NoClassDefFoundError: net/minecraft/client/renderer/...
OR
Method net.minecraft.client.Minecraft.getInstance() not found3. Remove client-side mods
Delete the client-only mods from the 'mods' folder on your server via File Manager or SFTP. Restart your server.
Still stuck?
Tell support what you already tried so we can help faster.