When moving contraptions collide in certain degenerate or exact-overlap cases, Create's collision manifold fails to record a separation axis, leaving it null. The game then tries to read .x on that null Vec3 and the server crashes:
java.lang.NullPointerException: Cannot read field "x" because "mf.axis" is null at ...ContinuousOBBCollider.collideMany(ContinuousOBBCollider.java:153) This mod uses a Mixin to intercept the two null-prone field reads (axis and normalAxis) and substitutes Vec3.ZERO when they're null. A zero vector makes that frame's collision contribution 0 — harmless — instead of crashing the server tick thread.
Details:
Lightweight — single mixin, no runtime overhead beyond a null check Doesn't modify Create's logic, just prevents the null dereference Works server-side (install on server only is fine, but safe on both sides) For Create 6.0.10 on NeoForge / Minecraft 1.21.1
How to Install Create OBB Collision Crash Fix (Mod)
Create OBB Collision Crash Fix by BlazeyCrazey is verified for Neoforge across Minecraft versions 1.21.1 (latest release: 1.0.0, file size: 3 KB). Follow the steps below to install it safely from ModCraft.tv:
- Click the Download button above and select your Minecraft version (1.21.1) and platform (Neoforge).
- Make sure you have the compatible loader or environment installed for Neoforge.
- Move the downloaded Create OBB Collision Crash Fix file into your Minecraft
.minecraft/modsfolder and launch the game.