{"record":{"id":"1a9e10b611ff0038","repo":"tensorflow/models","slug":"unknown-combine-fn","errorCode":null,"errorMessage":"unknown combine_fn `{}`.","messagePattern":"unknown combine_fn `(.+?)`\\.","errorType":"exception","errorClass":"ValueError","httpStatus":null,"severity":"error","filePath":"official/vision/modeling/decoders/nasfpn.py","lineNumber":286,"sourceCode":"      node0 = feats[input0]\n      node0_level = feat_levels[input0]\n      num_output_connections[input0] += 1\n      node0 = self._resample_feature_map(node0, node0_level, new_level)\n      node1 = feats[input1]\n      node1_level = feat_levels[input1]\n      num_output_connections[input1] += 1\n      node1 = self._resample_feature_map(node1, node1_level, new_level)\n\n      # Combine node0 and node1 to create new feat.\n      if block_spec.combine_fn == 'sum':\n        new_node = node0 + node1\n      elif block_spec.combine_fn == 'attention':\n        if node0_level >= node1_level:\n          new_node = self._global_attention(node0, node1)\n        else:\n          new_node = self._global_attention(node1, node0)\n      else:\n        raise ValueError('unknown combine_fn `{}`.'\n                         .format(block_spec.combine_fn))\n\n      # Add intermediate nodes that do not have any connections to output.\n      if block_spec.is_output:\n        for j, (feat, feat_level, num_output) in enumerate(\n            zip(feats, feat_levels, num_output_connections)):\n          if num_output == 0 and feat_level == new_level:\n            num_output_connections[j] += 1\n\n            feat_ = self._resample_feature_map(feat, feat_level, new_level)\n            new_node += feat_\n\n      new_node = self._activation(new_node)\n      new_node = self._conv_op(\n          filters=self._config_dict['num_filters'],\n          kernel_size=(3, 3),\n          padding='same',\n          **self._conv_kwargs)(new_node)","sourceCodeStart":268,"sourceCodeEnd":304,"githubUrl":"https://github.com/tensorflow/models/blob/e006f5f0d534913e49c1f1dae87364039fa607e2/official/vision/modeling/decoders/nasfpn.py#L268-L304","documentation":"Error \"unknown combine_fn `{}`.\" thrown in tensorflow/models.","triggerScenarios":"Thrown at official/vision/modeling/decoders/nasfpn.py:286 when the library encounters an invalid state.","commonSituations":"See trigger scenarios.","solutions":["Use a supported combine_fn such as 'attention', 'sum', or 'concat' in the NASFPN config.","Check the combine_fn value for typos."],"exampleFix":null,"handlingStrategy":null,"validationCode":null,"typeGuard":null,"tryCatchPattern":null,"preventionTips":[],"tags":[],"backgroundTag":null,"analyzedSha":"e006f5f0d534913e49c1f1dae87364039fa607e2","analyzedAt":"2026-08-24T14:09:15.576Z","schemaVersion":2},"datasetVersion":"2026-08-24T17:17:21.512Z"}