Unity 4 mecanim; 'Quaternion to Matrix conversion failed, input quaternion is invalid'

Question

I'm trying to animate a stick figure in Unity, with placeholder animations. Character is built/animated in Blender, exported to FBX. When imported to Unity, everything appears correct in the editor. All animations are imported, and i can preview them normally.

I set up the "rig" section of the model import to use generic rigging. This creates the avatar which is used in mecanim.

I set up a simple "walkForward" animation, and setup mecanim parameters to get it called when the player moved forward; all that works. The animation is called at the right times.

However, during play, as soon as any animation is started on the avatar, the model disappears, and a flood of error messages appear in the console, stating

Quaternion to Matrix conversion failed because input Quaternion is invalid {-1.#IND00, -1.#IND00, -1.#IND00, -1.#IND00} |=-1#IND00

I'm not altering the animation with any scripts of my own, it's all mecanim. Is there a setting i'm missing?

I'm using Unity 4.3.0.0f4, building/exporting my mesh with Blender (latest).

Answer 1

I was never able to find a proper solution to this problem - I eventually gave up on Unity 4. This year I've returned and found that Unity 5 correctly imports the exact same models/animations and everything works as expected.

So; solution is to update to unity 5.