Cobblemon Server Fix

What is this mod?

Cobblemon Server Fix is a lightweight compatibility patch that prevents a range of client crashes caused by incomplete data synchronization between a Cobblemon dedicated server and connecting clients. It was originally developed to solve persistent, hard-to-diagnose crashes in Cobblemon + Create - Pokémon meets Industrial Revolution!, but it is completely modpack-agnostic and safe to use in any Cobblemon-based pack running on a dedicated server.

What problem does it solve?

On some dedicated servers, Cobblemon's species data fails to fully synchronize to connecting clients. This results in:

Clients crashing with UninitializedPropertyAccessException: lateinit property species has not been initialized
Pokémon showing as "Error Rendering" in JEI/EMI
Crashes when opening the PC, viewing the party, evolving Pokémon, or interacting with certain species
Crashes triggered by ability-update and form-update packets referencing data the client never fully received

Oddly, the exact same Pokémon are affected consistently across different servers and machines, and the issue disappears if a player briefly loads a singleplayer world before reconnecting, strongly pointing to a synchronization timing bug, not a hardware or config issue.

What likely causes this?

The most consistent common factor across affected setups is the Sinytra Connector, used to run Fabric-only mods on NeoForge. Its interaction with Cobblemon's data-sync and resource-loading pipeline appears to disrupt the timing of species initialization on the client, leaving certain FormData objects (and their internal behaviour.parent references) incomplete when the client tries to use them. This mod does not disable or replace the Connector, it works around the resulting incomplete state defensively.

What does the mod actually do?

Forces Cobblemon to properly re-initialize all species data server-side once a player's data sync completes
Adds safe fallback handling on the client for FormData.species and FormPokemonBehaviour.parent when they arrive uninitialized, preventing hard crashes
Adds a narrow, targeted fix for ability-update packets referencing abilities the client hasn't fully registered yet

It does not modify saves, drop tables, spawns, recipes, or any core Cobblemon gameplay system. It only intervenes at the exact points where missing sync data would otherwise crash the game.

Installation

This mod must be installed on both the client and the dedicated server to work correctly. It has no effect in singleplayer beyond being harmlessly inert.

License

This mod is released under the MIT License. You are free to use, modify, redistribute, and include it in any modpack, public or private, without needing to ask permission. Credit is appreciated but not required.