{"record":{"id":"75ae961f327bc7c4","repo":"tensorflow/models","slug":"block-fn-is-not-supported-75ae96","errorCode":null,"errorMessage":"Block fn `{}` is not supported.","messagePattern":"Block fn `(.+?)` is not supported\\.","errorType":"exception","errorClass":"ValueError","httpStatus":null,"severity":"error","filePath":"official/vision/modeling/backbones/resnet_unet.py","lineNumber":397,"sourceCode":"              x)\n      x = self._norm(\n          axis=bn_axis,\n          momentum=norm_momentum,\n          epsilon=norm_epsilon,\n          trainable=bn_trainable)(\n              x)\n      x = tf_utils.get_activation(activation, use_keras_layer=True)(x)\n    else:\n      x = layers.MaxPool2D(pool_size=3, strides=2, padding='same')(x)\n\n    endpoints = {}\n    for i, spec in enumerate(RESNET_SPECS[model_id]):\n      if spec[0] == 'residual':\n        block_fn = nn_blocks.ResidualBlock\n      elif spec[0] == 'bottleneck':\n        block_fn = nn_blocks.BottleneckBlock\n      else:\n        raise ValueError('Block fn `{}` is not supported.'.format(spec[0]))\n      x = self._block_group(\n          inputs=x,\n          filters=int(spec[1] * self._depth_multiplier),\n          strides=(1 if i == 0 else 2),\n          block_fn=block_fn,\n          block_repeats=spec[2],\n          stochastic_depth_drop_rate=nn_layers.get_stochastic_depth_rate(\n              self._init_stochastic_depth_rate, i + 2, 8),\n          name='block_group_l{}'.format(i + 2))\n      endpoints[str(i + 2)] = x\n\n    norm_layer = lambda: tf_keras.layers.LayerNormalization(epsilon=1e-6)\n    for i in range(len(upsample_filters)):  # pyrefly: ignore[bad-argument-type]\n      backbone_feature = layers.Conv2D(\n          filters=int(upsample_filters[i] * stem_depth_multiplier),  # pyrefly: ignore[unsupported-operation]\n          kernel_size=1,\n          strides=1,\n          use_bias=False,","sourceCodeStart":379,"sourceCodeEnd":415,"githubUrl":"https://github.com/tensorflow/models/blob/e006f5f0d534913e49c1f1dae87364039fa607e2/official/vision/modeling/backbones/resnet_unet.py#L379-L415","documentation":"Error \"Block fn `{}` is not supported.\" thrown in tensorflow/models.","triggerScenarios":"Thrown at official/vision/modeling/backbones/resnet_unet.py:397 when the library encounters an invalid state.","commonSituations":"See trigger scenarios.","solutions":["Use a supported block_fn: 'bottleneck' or 'basic'.","Check the block_fn value in the backbone config 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"}