VRChat lip sync not working (mouth not moving when you talk) - visemes and expression fix

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What you see on screen:

What it means

Lip sync needs the Avatar Descriptor's Lip Sync mode and visemes set up (Viseme Blend Shape is the recommended mode). If it works normally but stops while an expression is on, the expression animation also drives the lip sync blendshapes (vrc.v_aa, etc.) and holds the mouth shape.

Common causes

• Lip Sync mode isn't set, or the visemes aren't assigned on the Avatar Descriptor
• The SIL viseme shape was empty and Unity removed it on import
• You made an expression that includes a mouth shape
• An expression set or gimmick animation includes vrc.v_ blendshapes

How to fix it

1. On the Avatar Descriptor, open Lip Sync and press Auto Detect (or set Viseme Blend Shape and pick each viseme)
2. If only the expression breaks it, open the expression animation (.anim) and look for blendshapes starting with vrc.v_
3. If found, rebuild it with a mouth shape that isn't a lip sync viseme (or delete that row)
4. If you want lip sync to win while talking, move the mouth part to a separate layer

Before you change anything, make a full copy of your project folder so you can go back.

Related errors

• VRChat eyes twitching / blinking during a closed-eye expression
• VRChat hand gestures not working (face or hands don't change)
• VRChat "This avatar uses a mixture of Write Defaults"
• VRChat expressions or toggles not working: FX layer weight is 0

See other errors