{"record":{"id":"1c390a8d5c72371e","repo":"vllm-project/vllm","slug":"the-quantization-method-s-is-deprecated-and-will","errorCode":null,"errorMessage":"The quantization method %s is deprecated and will be removed in future versions of vLLM. To bypass, set `--allow-deprecated-quantization`.","messagePattern":"The quantization method (.+?) is deprecated and will be removed in future versions of vLLM\\. To bypass, set `--allow-deprecated-quantization`\\.","errorType":"validation","errorClass":"ValueError","httpStatus":null,"severity":"error","filePath":"vllm/config/model.py","lineNumber":1296,"sourceCode":"                )\n\n        if self.quantization is not None:\n            if self.quantization not in supported_quantization:\n                raise ValueError(\n                    f\"Unknown quantization method: {self.quantization}. Must \"\n                    f\"be one of {supported_quantization}.\"\n                )\n            current_platform.verify_quantization(self.quantization)\n\n        if self.quantization in me_quant.DEPRECATED_QUANTIZATION_METHODS:\n            if self.allow_deprecated_quantization:\n                logger.warning(\n                    \"The quantization method %s is deprecated \"\n                    \"and will be removed in future versions of vLLM.\",\n                    self.quantization,\n                )\n            else:\n                raise ValueError(\n                    \"The quantization method %s is deprecated \"\n                    \"and will be removed in future versions of vLLM. To bypass, \"\n                    \"set `--allow-deprecated-quantization`.\",\n                    self.quantization,\n                )\n\n    def _verify_cuda_graph(self) -> None:\n        # CUDAGraph capture not supported for encoder-decoder models on ROCm\n        unsupported_rocm = self.is_encoder_decoder\n        if unsupported_rocm and not self.enforce_eager and current_platform.is_rocm():\n            logger.warning(\n                \"CUDA graph is not supported for %s on ROCm yet, fallback \"\n                \"to eager mode.\",\n                self.model_arch_config.model_type,\n            )\n            self.enforce_eager = True\n\n    def _verify_with_expert_parallelism(self) -> None:","sourceCodeStart":1278,"sourceCodeEnd":1314,"githubUrl":"https://github.com/vllm-project/vllm/blob/c794754062d49a8fdb63ab3c5215b488b865030c/vllm/config/model.py#L1278-L1314","documentation":"Raised when the requested quantization method is listed in DEPRECATED_QUANTIZATION_METHODS and the user has not opted in with allow_deprecated_quantization. vLLM removes old quantization formats over time; this error forces users to acknowledge the pending removal. With the flag set, the same condition only logs a warning and startup continues.","triggerScenarios":"Launching a model whose --quantization (or HF config quantization_config) resolves to a method in vllm/model_executor/models/me_quant.DEPRECATED_QUANTIZATION_METHODS, without passing --allow-deprecated-quantization.","commonSituations":"Upgrading vLLM to a release that deprecates a quantization format (e.g. an old AWQ/GPTQ variant) while serving checkpoints quantized with it; loading a community checkpoint whose config.json embeds the deprecated method name.","solutions":["Switch the checkpoint to a currently supported quantization method (re-quantize or download a newer checkpoint build).","If you accept the removal risk, launch with --allow-deprecated-quantization (CLI) or allow_deprecated_quantization=True (Llm/AsyncEngineArgs).","Check the vLLM release notes / changelog for the deprecation announcement and the recommended replacement format."],"exampleFix":"# before\nvllm serve my-model --quantization <deprecated-method>\n# after\nvllm serve my-model --quantization <deprecated-method> --allow-deprecated-quantization","handlingStrategy":"validation","validationCode":"from vllm.model_executor.models import me_quant\ndef check_quant_not_deprecated(q: str) -> bool:\n    return q not in me_quant.DEPRECATED_QUANTIZATION_METHODS\n# before LLM(...): if deprecated, either re-quantize or pass\n# allow_deprecated_quantization=True deliberately.","typeGuard":null,"tryCatchPattern":"except ValueError as e:\n    if 'deprecated' in str(e) and 'allow-deprecated-quantization' in str(e):\n        retry with allow_deprecated_quantization=True after logging a removal-risk warning","preventionTips":["Track vLLM release notes for quantization deprecation announcements before upgrading.","Prefer re-quantizing checkpoints to supported formats instead of relying on the bypass flag.","Assert your quantization method against DEPRECATED_QUANTIZATION_METHODS in CI startup checks."],"tags":["quantization","deprecation","startup","config"],"backgroundTag":null,"analyzedSha":"c794754062d49a8fdb63ab3c5215b488b865030c","analyzedAt":"2026-08-14T21:17:39.825Z","schemaVersion":2},"datasetVersion":"2026-08-15T17:31:12.345Z"}