Programming Assignment: Deep Neural Network - Application: Grader not working properly

[ValidateApp | INFO] Validating ‘/home/jovyan/work/submitted/courseraLearner/W4A2/Deep Neural Network - Application.ipynb’
[ValidateApp | INFO] Executing notebook with kernel: python3
[ValidateApp | ERROR] Timeout waiting for execute reply (30s).
[ValidateApp | ERROR] Interrupting kernel
Tests failed on 1 cell(s)! These tests could be hidden. Please check your submission.

The following cell failed:

parameters, costs = L_layer_model(train_x, train_y, layers_dims, num_iterations = 1...

print("Cost after first iteration: " + str(costs[0]))


Please show us the actual failure and any exception trace that you get running that L_layer_model test.