Developer Reveals LLM Fine-Tuning Fragility and Training Crashes

Developers highlighted the extreme fragility of LLMs during training and fine-tuning, revealing that soft data duplication involving rare words can trigger gradient explosions in GRPO. This instability means models can degrade into outputting gibberish after just two training steps, a problem further exacerbated by quantization.

2026-08-02 ~ 2026-08-02 · 3 related posts

• Soft Data Duplication Blows Out Gradients: Root Cause of GRPO Training Collapse — ivan_bezdomny · 2026-08-02
• Training LLMs is Like Riding a Motorcycle: Fragility to Data Duplication — ivan_bezdomny · 2026-08-02
• From Good Text to Gibberish in Two Steps: Uncovering LLM Finetuning Instability — ivan_bezdomny · 2026-08-02