Why GRPO collapses on multi-turn agent training, and how to stabilize advantage estimation

burkov · x · 2026-10-20

Burkov highlights an in-depth article on a key fragility in agentic RL: GRPO, the most widely used method, was designed for single-turn tasks and tends to become unstable or collapse outright on multi-turn agent tasks requiring sequential decisions and environmental feedback. The article investigates more stable ways to estimate advantages — the signal telling the model which actions were better — and why current approaches fail in agentic settings. Essential reading for anyone building or depending on agent systems.

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