Seven official quantized model tags solve almost nothing, and rebuilding them proved they were never corrupted
AspireAI community · arXiv
An audit of the Ollama library and popular Hugging Face files found that quantized model artifacts can be byte-perfect and still functionally broken. The team tested all 305 eligible code-capable GGUF tags across 15 model lines plus 22 community files; seven official tags (2.3%) solved at most six of 164 HumanEval+ tasks, and all were low-bit quantizations of models with four billion parameters or fewer. Rebuilding five suspects from the original weights matched the registry files tensor for tensor, so nothing was corrupted - the quantizer was simply broken. With weights, toolchain and tensor mix held fixed, adding an importance matrix lifted Qwen2.5-Coder-3B from zero to 76-113 of 164 tasks at three quantization levels, while the same recipe left the 1.5B model working, so the recipe alone does not predict failure. The authors release the audit data and a quantcheck tool, and recommend screening low-bit tags before publication. Note the paper's v3 revision walks back part of its diagnosis for one community file pair, which a chat-template test shows fails for lack of a template rather than a backend defect.
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