Step 3.5 Flash expert norm blew up 5700x while training loss hid the failure
Nouamanetazi · x · 2026-11-06
The MoE handbook shows how a run can go wrong while loss looks fine: in one layer of Step 3.5 Flash, the largest expert's output norm grew from 14x to 5,700x the layer's median, invisible in the training loss. A video simulates this alongside two other failures that per-layer signals catch.
Related event: Hugging Face Releases Free MoE Training Handbook Built on 800K GPU Hours(20 posts)→
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