Grader doesn't work

C5 W2 A2
What should I do?

A few days ago, this user faced the same error in C5 W3 A2. Are you facing this in the W3 assignment (Trigger_word_detection_v2a)? Have you passed all the exercise tests? If so, then Kernel → Restart & Clear Output and then running all the cells may help. If you didn’t pass all the test, you need to look at your code. What is in Cell # 21?

That specific error message most likely means that there is some part of the code that you didn’t complete. Please search for “None” in the notebook: they frequently use that in the template code to indicate places where you need to complete some code. Of course there can be legitimate syntactic uses of “None”, but you need to understand whether each instance of “None” is or is not something you need to change.