AttributeError: 'Operation' object has no attribute '_c_op'

[888yyh]

tensorflow2.1
dear professor, i met this error,hope you could help me.Thank you.
Traceback (most recent call last):
File "run.py", line 118, in
imgs_mask_test = model.predict(imagestest, verbose=1)
File "/home/ma-user/anaconda3/envs/TensorFlow-2.1.0/lib/python3.7/site-packages/tensorflow_core/python/keras/engine/training.py", line 1013, in predict
use_multiprocessing=use_multiprocessing)
File "/home/ma-user/anaconda3/envs/TensorFlow-2.1.0/lib/python3.7/site-packages/tensorflow_core/python/keras/engine/training_v2.py", line 498, in predict
workers=workers, use_multiprocessing=use_multiprocessing, **kwargs)
File "/home/ma-user/anaconda3/envs/TensorFlow-2.1.0/lib/python3.7/site-packages/tensorflow_core/python/keras/engine/training_v2.py", line 475, in _model_iteration
total_epochs=1)
File "/home/ma-user/anaconda3/envs/TensorFlow-2.1.0/lib/python3.7/site-packages/tensorflow_core/python/keras/engine/training_v2.py", line 128, in run_one_epoch
batch_outs = execution_function(iterator)
File "/home/ma-user/anaconda3/envs/TensorFlow-2.1.0/lib/python3.7/site-packages/tensorflow_core/python/keras/engine/training_v2_utils.py", line 98, in execution_function
distributed_function(input_fn))
File "/home/ma-user/anaconda3/envs/TensorFlow-2.1.0/lib/python3.7/site-packages/tensorflow_core/python/eager/def_function.py", line 568, in call
result = self._call(*args, **kwds)
File "/home/ma-user/anaconda3/envs/TensorFlow-2.1.0/lib/python3.7/site-packages/tensorflow_core/python/eager/def_function.py", line 615, in _call
self._initialize(args, kwds, add_initializers_to=initializers)
File "/home/ma-user/anaconda3/envs/TensorFlow-2.1.0/lib/python3.7/site-packages/tensorflow_core/python/eager/def_function.py", line 497, in _initialize
*args, **kwds))
File "/home/ma-user/anaconda3/envs/TensorFlow-2.1.0/lib/python3.7/site-packages/tensorflow_core/python/eager/function.py", line 2389, in _get_concrete_function_internal_garbage_collected
graph_function, _, _ = self._maybe_define_function(args, kwargs)
File "/home/ma-user/anaconda3/envs/TensorFlow-2.1.0/lib/python3.7/site-packages/tensorflow_core/python/eager/function.py", line 2703, in _maybe_define_function
graph_function = self._create_graph_function(args, kwargs)
File "/home/ma-user/anaconda3/envs/TensorFlow-2.1.0/lib/python3.7/site-packages/tensorflow_core/python/eager/function.py", line 2593, in _create_graph_function
capture_by_value=self._capture_by_value),
File "/home/ma-user/anaconda3/envs/TensorFlow-2.1.0/lib/python3.7/site-packages/tensorflow_core/python/framework/func_graph.py", line 978, in func_graph_from_py_func
func_outputs = python_func(*func_args, **func_kwargs)
File "/home/ma-user/anaconda3/envs/TensorFlow-2.1.0/lib/python3.7/site-packages/tensorflow_core/python/eager/def_function.py", line 439, in wrapped_fn
return weak_wrapped_fn().wrapped(*args, **kwds)
File "/home/ma-user/anaconda3/envs/TensorFlow-2.1.0/lib/python3.7/site-packages/tensorflow_core/python/keras/engine/training_v2_utils.py", line 85, in distributed_function
per_replica_function, args=args)
File "/home/ma-user/anaconda3/envs/TensorFlow-2.1.0/lib/python3.7/site-packages/tensorflow_core/python/distribute/distribute_lib.py", line 763, in experimental_run_v2
return self._extended.call_for_each_replica(fn, args=args, kwargs=kwargs)
File "/home/ma-user/anaconda3/envs/TensorFlow-2.1.0/lib/python3.7/site-packages/tensorflow_core/python/distribute/distribute_lib.py", line 1819, in call_for_each_replica
return self._call_for_each_replica(fn, args, kwargs)
File "/home/ma-user/anaconda3/envs/TensorFlow-2.1.0/lib/python3.7/site-packages/tensorflow_core/python/distribute/distribute_lib.py", line 2164, in _call_for_each_replica
return fn(*args, **kwargs)
File "/home/ma-user/anaconda3/envs/TensorFlow-2.1.0/lib/python3.7/site-packages/tensorflow_core/python/autograph/impl/api.py", line 292, in wrapper
return func(*args, **kwargs)
File "/home/ma-user/anaconda3/envs/TensorFlow-2.1.0/lib/python3.7/site-packages/tensorflow_core/python/keras/engine/training_v2_utils.py", line 212, in _predict_on_batch
result = predict_on_batch(model, x)
File "/home/ma-user/anaconda3/envs/TensorFlow-2.1.0/lib/python3.7/site-packages/tensorflow_core/python/keras/engine/training_v2_utils.py", line 556, in predict_on_batch
return predict_on_batch_fn(inputs) # pylint: disable=not-callable
File "/home/ma-user/anaconda3/envs/TensorFlow-2.1.0/lib/python3.7/site-packages/tensorflow_core/python/keras/engine/base_layer.py", line 778, in call
outputs = call_fn(cast_inputs, *args, **kwargs)
File "/home/ma-user/anaconda3/envs/TensorFlow-2.1.0/lib/python3.7/site-packages/tensorflow_core/python/keras/engine/network.py", line 717, in call
convert_kwargs_to_constants=base_layer_utils.call_context().saving)
File "/home/ma-user/anaconda3/envs/TensorFlow-2.1.0/lib/python3.7/site-packages/tensorflow_core/python/keras/engine/network.py", line 891, in _run_internal_graph
output_tensors = layer(computed_tensors, **kwargs)
File "/home/ma-user/anaconda3/envs/TensorFlow-2.1.0/lib/python3.7/site-packages/tensorflow_core/python/keras/engine/base_layer.py", line 778, in call
outputs = call_fn(cast_inputs, *args, **kwargs)
File "/home/ma-user/anaconda3/envs/TensorFlow-2.1.0/lib/python3.7/site-packages/tensorflow_core/python/keras/layers/convolutional.py", line 209, in call
outputs = self._convolution_op(inputs, self.kernel)
File "/home/ma-user/anaconda3/envs/TensorFlow-2.1.0/lib/python3.7/site-packages/tensorflow_core/python/ops/nn_ops.py", line 1135, in call
return self.conv_op(inp, filter)
File "/home/ma-user/anaconda3/envs/TensorFlow-2.1.0/lib/python3.7/site-packages/tensorflow_core/python/ops/nn_ops.py", line 640, in call
return self.call(inp, filter)
File "/home/ma-user/anaconda3/envs/TensorFlow-2.1.0/lib/python3.7/site-packages/tensorflow_core/python/ops/nn_ops.py", line 616, in _with_space_to_batch_call
block_shape=self.dilation_rate)
File "/home/ma-user/anaconda3/envs/TensorFlow-2.1.0/lib/python3.7/site-packages/tensorflow_core/python/ops/array_ops.py", line 3303, in required_space_to_batch_paddings
const_block_shape = tensor_util.constant_value(block_shape)
File "/home/ma-user/anaconda3/envs/TensorFlow-2.1.0/lib/python3.7/site-packages/tensorflow_core/python/framework/tensor_util.py", line 827, in constant_value
ret = _ConstantValue(tensor, partial)
File "/home/ma-user/anaconda3/envs/TensorFlow-2.1.0/lib/python3.7/site-packages/tensorflow_core/python/framework/tensor_util.py", line 673, in _ConstantValue
if tensor.op.type == "Const":
File "/home/ma-user/anaconda3/envs/TensorFlow-2.1.0/lib/python3.7/site-packages/tensorflow_core/python/framework/ops.py", line 2220, in type
return c_api.TF_OperationOpType(self._c_op)
AttributeError: 'Operation' object has no attribute '_c_op'