# The LR Death Spiral 🧨 — Muon/Dion3 Debugging Saga > Source: > Published: 2026-09-22 01:42:49+00:00 I was supposed to be running optimizer experiments for my upcoming PyTorch Conference talk. Instead, my learning rate entered a death spiral. I was testing AdamW, Muon, Dion, and the latest Dion3 implementation in OLMo-core—and Dion3 broke things in some very interesting ways. Turns out the debugging trail involved distributed optimizer state, LR scheduling, and a particularly nasty PyTorch tensor aliasing trap. A fun debugging experience nonetheless. I wrote up the whole adventure here: More optimizer experiments coming before PyTorch Con!