Autograder not working

All of my answers are correct, but I get a zero on the autograder. The only error message I get in the notebook itself is for excercise 1, where it says "Error: Wrong shape. " The output is a float, there should be no shape issue. I believe the autograder is not working. Can someone please check?

Hi @Bradley_Merrill_Thom,

Can you share your lab ID with me ? In the assignment, when you click the top right “Help” button, a panel will open and your lab ID will be shown at the bottom.
I shall take a look.

When you reply back, kindly tag me in the post so that I’m notified.


@Mubsi Here is my lab ID qkbonadh

Hi @Bradley_Merrill_Thom,

The autograder is working fine.

You mentioned you are passing all the tests within the notebook, which you are, except for Ex 1’s unit test. Those, you are failing.

You must understand that only matching the expected outputs does not mean that you have passed the unit test, you also need to get the All tests passed. output as well (which also happens to be part of the expected output). Since you are failing the unit test in the notebook, you are failing the autograder test as well. And like a compiler, the autograder works in a sequential manner. If there’s a error in between, it would stop there, and not continue ahead.

As for your mistake, I have left the comment in your Ex 1. You were using the isna function, when the hints ask you to use the isnull function.


I am also getting the “wrong shape” error here. The shape check fails, because my function outputs a number of datatype numpy.float64 which has the shape (), while the test case expects a result of type float, which has no shape attribute.

The solution is, to typecast the result of ‘fraction_rows_missing()’ to the float datatype before returning it:

def fraction_rows_missing(df):
    return float( YOUR SOLUTION HERE )



Thanks, Marco!
It helps me too

Just a hint:
I had also the same problem. After my investigation the problem was caused by using “np.sum()”, but if you use a default “sum()” function, it will probably solve your problem with a wrong shape. At least it worked for me.

Hi Mubsi,
I’ve been struggling with my assignment of week 2 in AI for medical prognosis course because of grading error. The outputs of all my answers have met the expectations & I modified them several times. I don’t get any error in the notebook itself. After I submit the assignment, it’ successfully submitted. At the end I get grading error with 0/6 grade. The message I get is: Please try optimizing the efficiency of your solution and submit again. You can also visit the discussion forum to see if your peers have experienced and found resolutions for similar errors, or if course staff have provided prior guidance for these errors… If the error isn’t resolved in 24 hours, please reach out to Coursera through our Help Center.
I modifies my answer & I got even better output than I got before, which was actually closer to the expected output. However, I still get a grading error.

Hi @Ehab_Mohamed_Elgamal,

Do you still need help with this ?


Hi Mr Muhammad,
Thanks a lot for your response. I would send you my lab Id within few hours. I’m sorry I’ve been busy for the last couple of days. I really appreciate your help.

Hi @Ehab_Mohamed_Elgamal,

Indeed, you are complicating things in your assignment.

For example, in multiple places you have set as 'max_depth': list(range(1, 101)) . This is using up a lot of resources in not just the assignment, but also for the grader. Try doing it in a simpler way.