Users have reported that working in ACES or high-dynamic-range color spaces can cause the ML engine to fail. Switching to OCIO Legacy or Rec.709 within Mocha often restores the render.
If you meant you need this as a log line or error report for support (e.g., for Boris FX Mocha Pro or Adobe After Effects), here's a complete example:
If you are facing this error, work through these verified troubleshooting steps to get your render back on track. 1. Purge Cache and Reset Mocha