{"record":{"id":"a19946a42bf8e6a3","repo":"sgl-project/sglang","slug":"presence-penalty-must-be-in-2-2-got-self-pre","errorCode":null,"errorMessage":"presence_penalty must be in [-2, 2], got {self.presence_penalty}.","messagePattern":"presence_penalty must be in \\[-2, 2\\], got (.+?)\\.","errorType":"validation","errorClass":"ValueError","httpStatus":null,"severity":"error","filePath":"python/sglang/srt/sampling/sampling_params.py","lineNumber":179,"sourceCode":"        if not 0.0 < self.top_p <= 1.0:\n            raise ValueError(f\"top_p must be in (0, 1], got {self.top_p}.\")\n        if not 0.0 <= self.min_p <= 1.0:\n            raise ValueError(f\"min_p must be in [0, 1], got {self.min_p}.\")\n        if self.top_k < 1 or self.top_k == -1:\n            raise ValueError(\n                f\"top_k must be -1 (disable) or at least 1, got {self.top_k}.\"\n            )\n        if not -2.0 <= self.frequency_penalty <= 2.0:\n            raise ValueError(\n                \"frequency_penalty must be in [-2, 2], got \"\n                f\"{self.frequency_penalty}.\"\n            )\n        if not -2.0 <= self.presence_penalty <= 2.0:\n            raise ValueError(\n                \"presence_penalty must be in [-2, 2], got \" f\"{self.presence_penalty}.\"\n            )\n        if not 0.0 < self.repetition_penalty <= 2.0:\n            raise ValueError(\n                \"repetition_penalty must be in (0, 2] (1.0 = no penalty), \"\n                f\"got {self.repetition_penalty}.\"\n            )\n        if not 0 <= self.min_new_tokens:\n            raise ValueError(\n                f\"min_new_tokens must be in [0, max_new_tokens], got \"\n                f\"{self.min_new_tokens}.\"\n            )\n        if self.max_new_tokens is not None:\n            if self.max_new_tokens < 0:\n                raise ValueError(\n                    f\"max_new_tokens must be at least 0, got {self.max_new_tokens}.\"\n                )\n            if not self.min_new_tokens <= self.max_new_tokens:\n                raise ValueError(\n                    f\"min_new_tokens must be in [0, max_new_tokens({self.max_new_tokens})], got \"\n                    f\"{self.min_new_tokens}.\"\n                )","sourceCodeStart":161,"sourceCodeEnd":197,"githubUrl":"https://github.com/sgl-project/sglang/blob/0132848349585cfe6aae51c4941cbae872505f8a/python/sglang/srt/sampling/sampling_params.py#L161-L197","documentation":"SamplingParams.verify() requires presence_penalty to lie in [-2, 2] (OpenAI-compatible range). presence_penalty adds a flat penalty to tokens that have already appeared at least once; values outside the range raise this ValueError during normalize()/verify().","triggerScenarios":"Passing SamplingParams(presence_penalty=2.5) or below -2; OpenAI-style API requests with out-of-range presence_penalty forwarded to SGLang.","commonSituations":"Proxy servers forwarding unvalidated OpenAI request fields; experiment scripts sweeping penalties outside the legal range; users assuming 0-10 scale.","solutions":["Clamp presence_penalty to [-2, 2]","Add request validation middleware for penalty fields","Use 0.0 to disable"],"exampleFix":"# before\nparams = SamplingParams(presence_penalty=penalty)\n# after\nparams = SamplingParams(presence_penalty=max(-2.0, min(2.0, penalty)))","handlingStrategy":"validation","validationCode":"presence_penalty = max(-2.0, min(2.0, presence_penalty))\nparams = SamplingParams(presence_penalty=presence_penalty)","typeGuard":"def valid_presence_penalty(p):\n    return isinstance(p,(int,float)) and -2.0 <= p <= 2.0","tryCatchPattern":"try:\n    llm.generate(prompts, SamplingParams(presence_penalty=p))\nexcept ValueError as e:\n    if 'presence_penalty' in str(e):\n        p = 0.0\n    else:\n        raise","preventionTips":["Clamp presence_penalty to [-2, 2] for OpenAI-API compatibility","Use 0.0 to disable"],"tags":["sampling-params","presence-penalty","validation","sglang"],"backgroundTag":"sampling-parameter-validation-failed","analyzedSha":"0132848349585cfe6aae51c4941cbae872505f8a","analyzedAt":"2026-08-28T05:10:05.995Z","schemaVersion":2},"datasetVersion":"2026-08-28T06:17:29.519Z"}