{"record":{"id":"f7bf0ac6854b6aed","repo":"sgl-project/sglang","slug":"unsupported-activation-hidden-act-only-silu-is-f7bf0a","errorCode":null,"errorMessage":"Unsupported activation: {hidden_act}. Only silu is supported for now.","messagePattern":"Unsupported activation: (.+?)\\. Only silu is supported for now\\.","errorType":"validation","errorClass":"ValueError","httpStatus":null,"severity":"critical","filePath":"python/sglang/srt/models/baichuan.py","lineNumber":108,"sourceCode":"        prefix: str = \"\",\n    ):\n        super().__init__()\n        self.gate_up_proj = MergedColumnParallelLinear(\n            hidden_size,\n            [intermediate_size] * 2,\n            bias=False,\n            quant_config=quant_config,\n            prefix=add_prefix(\"gate_up_proj\", prefix),\n        )\n        self.down_proj = RowParallelLinear(\n            intermediate_size,\n            hidden_size,\n            bias=False,\n            quant_config=quant_config,\n            prefix=add_prefix(\"down_proj\", prefix),\n        )\n        if hidden_act != \"silu\":\n            raise ValueError(\n                f\"Unsupported activation: {hidden_act}. \"\n                \"Only silu is supported for now.\"\n            )\n        self.act_fn = SiluAndMul()\n\n    def forward(self, x):\n        gate_up, _ = self.gate_up_proj(x)\n        x = self.act_fn(gate_up)\n        x, _ = self.down_proj(x)\n        return x\n\n\nclass BaiChuanAttention(nn.Module):\n    \"\"\"Multi-headed attention from 'Attention Is All You Need' paper\"\"\"\n\n    def __init__(\n        self,\n        hidden_size: int,","sourceCodeStart":90,"sourceCodeEnd":126,"githubUrl":"https://github.com/sgl-project/sglang/blob/0132848349585cfe6aae51c4941cbae872505f8a/python/sglang/srt/models/baichuan.py#L90-L126","documentation":"The Baichuan MLP only implements SwiGLU; config.hidden_act must be exactly 'silu'. Any other value fails at initialization.","triggerScenarios":"Loading a Baichuan model whose config.json hidden_act is not \"silu\".","commonSituations":"Modified configs from fine-tuning pipelines; activation renamed during checkpoint conversion.","solutions":["Set \"hidden_act\": \"silu\" in config.json","Use an unmodified Baichuan checkpoint"],"exampleFix":"// before\n\"hidden_act\": \"gelu\"\n// after\n\"hidden_act\": \"silu\"","handlingStrategy":"validation","validationCode":"assert config.hidden_act == \"silu\"","typeGuard":null,"tryCatchPattern":null,"preventionTips":["Keep Baichuan config untouched"],"tags":["activation","config-validation","baichuan"],"backgroundTag":"unsupported-activation-function","analyzedSha":"0132848349585cfe6aae51c4941cbae872505f8a","analyzedAt":"2026-08-28T05:10:05.995Z","schemaVersion":2},"datasetVersion":"2026-08-28T06:17:29.519Z"}