Prediction Failed on keras model in Google ML-Engine

I am working through a tutorial at the moment which covers using a Keras based model on Google's cloud services with their ML-Engine. At this stage I have the model working fine for local predictions etc, and have successfully placed the exported model into a GC-bucket. I have also created the google cloud ML-Engine model successfully. When I try to run a prediction off the cloud hosted model, I the following error is produced. Error: C:\mydir>gcloud ml-engine predict --model=[mymodel] --json-instances=sample_input_prescaled.json { "error": "Prediction failed: Error during model execution: AbortionError(code=StatusCode.FAILED_PRECONDITION, details=\"Attempting to use uninitialized value dense_4/bias\n\t [[Node: dense_4/bias/read = Identity[T=DT_FLOAT, _class=[\"loc:@dense_4/bias\"], _output_shapes=[[1]], _device=\"/job:localhost/replica:0/task:0/cpu:0\"](dense_4/bias)]]\")" } I can see that this error is refering to an uninitialised value 'dense_4', which looks like the last layer within the Keras model, but I'm not sure if/why this would be tripping up the process? Does anyone have some insight to the cause of this error message? Below is the keras model which I am using from the tutorial, and the json file for the test prediction. export_model.py import pandas as pd import keras from keras.models import Sequential from keras.layers import * import tensorflow as tf training_data_df = pd.read_csv("sales_data_training_scaled.csv") X = training_data_df.drop('total_earnings', axis=1).values Y = training_data_df[['total_earnings']].values # Define the model model = Sequential() model.add(Dense(50, input_dim=9, activation='relu')) model.add(Dense(100, activation='relu')) model.add(Dense(50, activation='relu')) model.add(Dense(1, activation='linear')) model.compile(loss='mean_squared_error', optimizer='adam') # Create a TensorBoard logger logger = keras.callbacks.TensorBoard( log_dir='logs', histogram_freq=5, write_graph=True ) # Train the model model.fit( X, Y, epochs=50, shuffle=True, verbose=2 ) # Load the separate test data set test_data_df = pd.read_csv("sales_data_test_scaled.csv") X_test = test_data_df.drop('total_earnings', axis=1).values Y_test = test_data_df[['total_earnings']].values test_error_rate = model.evaluate(X_test, Y_test, verbose=0) print("The mean squared error (MSE) for the test data set is: {}".format(test_error_rate)) model_builder = tf.saved_model.builder.SavedModelBuilder("exported_model") inputs = { 'input': tf.saved_model.utils.build_tensor_info(model.input) } outputs = { 'earnings': tf.saved_model.utils.build_tensor_info(model.output) } signature_def = tf.saved_model.signature_def_utils.build_signature_def( inputs=inputs, outputs=outputs, method_name=tf.saved_model.signature_constants.PREDICT_METHOD_NAME ) model_builder.add_meta_graph_and_variables( K.get_session(), tags=[tf.saved_model.tag_constants.SERVING], signature_def_map={ tf.saved_model.signature_constants.DEFAULT_SERVING_SIGNATURE_DEF_KEY: signature_def } ) model_builder.save() sample_input_prescaled.json { "input": [0.4999, 1.0, 0.0, 1.0, 0.0, 0.0, 0.0, 0.0, 0.5] }