JujutsuCraft Persistent Crash Fix

A small compatibility patch for JujutsuCraft 50/50.1 on Minecraft 1.20.1 Forge, created by MVQ1303.

What does it fix?

JujutsuCraft can occasionally crash while processing player advancements with an error similar to:

java.lang.NullPointerException:
Cannot read field "PlayerLevel" because "pVars" is null

at net.mcreator.jujutsucraft.procedures.CompletedAdvancementProcedure.execute(...)

This happens when JujutsuCraft attempts to access its custom player variables while the PlayerVariables object is unexpectedly unavailable.

This patch adds null-safe handling to the affected CompletedAdvancementProcedure, preventing a missing player-variable object from immediately crashing the server thread.

How does it work?

The mod uses a small Forge coremod transformer to patch JujutsuCraft at runtime.

Instead of modifying or redistributing JujutsuCraft itself, the patch intercepts player-variable field accesses inside the affected advancement procedure.

When the player variables are available, JujutsuCraft behaves normally.

If the variables are unexpectedly null, the patch supplies a safe default value or ignores the invalid write rather than allowing Java to throw a NullPointerException.

The patch currently targets only:

net.mcreator.jujutsucraft.procedures.CompletedAdvancementProcedure

It does not intentionally modify JujutsuCraft's world generation, techniques, mobs, structures, models, textures, or other gameplay systems.

Compatibility

• Minecraft: 1.20.1
• Mod Loader: Forge 47.x
• JujutsuCraft: 50 / 50.1
• Side: Client and Server
• Compatible with Jujutsu Vanilla World
• JujutsuCraft is required

Installation

1. Install JujutsuCraft 50/50.1.
2. Place JujutsuCraft Persistent Crash Fix in your mods folder.
3. Launch Minecraft normally.

Do not remove JujutsuCraft. This is an addon/compatibility patch and does not contain the original mod.

Credits

Created by MVQ1303

When entering a world with the mod installed, players will also receive a one-time chat message:

[JJC Crash Fix] Made by MVQ1303

Development Status

This project is currently experimental.

The present development build is being tested for a world-loading issue before being considered suitable for a stable release.

If you encounter another JujutsuCraft crash involving pVars or PlayerVariables, please provide the full crash report so support for the affected procedure can be investigated.

Disclaimer

This is an unofficial compatibility patch and is not affiliated with the original JujutsuCraft developer.

No JujutsuCraft code, assets, models, textures, or other copyrighted content are redistributed by this project.