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PhysBones Not Working in VRChat? Fix the Problem Fast

October 31, 2025 No comments yet

PhysBones are a critical feature for adding realistic movement and physics to avatars in VRChat, allowing for dynamic hair, tails, clothing, ears, and other body parts to move naturally. However, like any complex system, PhysBones can sometimes stop working unexpectedly. This can be frustrating for users who’ve spent time customizing their avatars or are trying to enjoy immersive experiences. Fortunately, most PhysBones issues are solvable with the right troubleshooting process.

In this article, we’ll break down common reasons why PhysBones might not work in VRChat and guide you through how to fix them quickly. From SDK updates to Unity settings, we’ll cover every essential step you need to get back to swinging tails and flowing skirts with ease.

What Are PhysBones?

PhysBones are a system developed for VRChat that replaced the older Dynamic Bones system. Designed to be more optimized and customizable, PhysBones allow creators to add joint-based physics to various parts of an avatar. These bones react to motion and VR controller inputs, letting things like ponytails bounce as you move or bunny ears wiggle when touched.

Without functioning PhysBones, avatars can appear stiff or broken, especially those designed with dynamic elements in mind.

Common Reasons Why PhysBones Aren’t Working

If your PhysBones aren’t responding, check the following potential causes:

  • Outdated VRChat SDK: Using an old SDK often causes compatibility problems with recent VRChat updates.
  • Incorrect Avatar Setup: PhysBones require proper hierarchy and component setup in Unity.
  • Broken Animator Controller: Avatars with a faulty animation controller may prevent physics from initializing correctly.
  • Missing or Incorrect PhysBone Components: If PhysBone scripts are missing or misconfigured, they won’t function.
  • Performance or Compatibility Settings: Certain settings in VRChat may alter physics behavior or disable them altogether.

Quick Fixes for PhysBones Not Working

1. Update Your VRChat SDK

The number one fix for most avatar-related issues is ensuring you’re using the latest version of VRChat SDK. Outdated SDKs can cause avatars to behave unpredictably, especially those using newer features like PhysBones.

  • Go to your Unity project folder.
  • Delete any old SDK folders (such as VRCSDK).
  • Download the latest SDK directly from the VRChat website.
  • Import it into Unity before uploading your avatar again.

2. Confirm PhysBone Components Are Active

Each part of your avatar that should use physics needs a PhysBone component attached. Check these in Unity:

  • Select the bone or mesh in the hierarchy.
  • Ensure the VRCPhysBone component is visible and enabled.
  • Set the proper root transform.
  • Verify settings such as pull, stiffness, and gravity are not set to zero unless that’s intentional.

3. Double-Check Colliders and Contacts

For reactive motion (such as touching ears or hair), PhysBones rely on colliders and contact receivers. If they aren’t correctly configured, interaction won’t work.

  • Ensure you have VRCContactReceiver and VRCPhysBoneCollider where needed.
  • Colliders should be a child of the bone they interact with.
  • Make sure their layers and interaction settings are correctly set.

4. Disable Legacy Dynamic Bones

Some avatars may still contain old Dynamic Bones components. While VRChat can technically handle both systems, having both active can cause problems.

In Unity:

  • Search for “DynamicBone” in the Inspector.
  • Remove or disable any instances.
  • Make sure all relevant parts are using VRCPhysBone instead.

5. Rebuild the Animator Controller

Sometimes, animation layers or states may interfere with the avatar’s physics system. If you’re comfortable with Animator Controllers, try these steps:

  • Create a new, clean Animator Controller.
  • Attach it to your avatar via the FX layer in the VRChat Avatar Descriptor.
  • Gradually reintroduce animations to isolate what could be breaking the PhysBones.

6. VRChat Settings to Enable

There are also in-game settings that affect how PhysBones behave:

  • Go to the VRChat Quick Menu → Settings → Performance Options.
  • Ensure Avatar Dynamics is enabled.
  • Turn on “Contacts” and “PhysBones” visibility.
  • Ensure Safety settings don’t block you from seeing others’ avatar bones.

In some cases, the avatar you’re testing may be hidden by VRChat’s safety filters, especially if its performance rating is “Very Poor.” You can override this with the Show Avatar option in the user menu.

Extra Tips For Success

  • Test in VRChat Dev Mode: Use a private world to eliminate other players or scripts as variables.
  • Avoid Multiple Roots: PhysBones need a clear hierarchy. Avoid assigning a PhysBone root to multiple objects with their own bones.
  • Reset Avatar ID: Sometimes simply resetting the Avatar ID and uploading as a new avatar refreshes issues.

Conclusion

PhysBones not working in VRChat can seriously affect your experience, but the fix is often just a few steps away. Whether it’s updating your SDK, tweaking your Unity setup, or checking in-game performance settings, most issues stem from manageable causes. With this guide, you should now be equipped to troubleshoot and resolve these problems swiftly.

As VRChat continues to evolve, keeping up with best practices and community updates is vital. Always refer to the official VRChat Documentation for the latest advice on PhysBones and avatar creation.

Frequently Asked Questions

  • Q: What is the difference between Dynamic Bones and PhysBones?
    A: PhysBones are VRChat’s new physics system, optimized for performance and flexibility. Dynamic Bones were imported through a third-party asset which is now deprecated.
  • Q: Can both Dynamic and PhysBones exist on the same avatar?
    A: Yes, but it is not recommended as it can cause instability or performance issues. Converting all physics to PhysBones is the best choice.
  • Q: I updated my SDK and PhysBones still don’t work. What else can I try?
    A: Try uploading your avatar as a new one instead of updating an existing one. This resets internal ID references that might be causing issues.
  • Q: My PhysBone reacts in Unity but not in VRChat. Why?
    A: This usually indicates issues with VRChat performance settings or avatar visibility settings. Make sure contacts and dynamics are enabled in-game.
  • Q: Are PhysBones more performance friendly than Dynamic Bones?
    A: Yes, PhysBones were developed to be lighter on resources, enabling better performance, especially in crowded public lobbies.