Cell #3. Can't compile the student's code. Error: IndexError('list index out of range')


In DLS, course-4, week3, programming assignment (UNet), I passed all the exercises tests, but the grader system shows 0/100. It shows the following grader report.

Cell #3. Can’t compile the student’s code. Error: IndexError(‘list index out of range’).

I tried the following steps:
a) Get the latest version of the lab (from help).
b) Restart kernel and clear outputs
c) save and checkpoint
d) Then, submitted again and again…but still, grades are 0/100

Could the course support team help me in this regard.Thanks

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Hi Pradeep,

Not sure if this thread might help you, but they were suggesting getting a copy of your current notebook before getting the fresh version and then copying the solutions from the old to the new one. Not sure if that is exactly what you did.
Anyway try several times submitting and check any potential changes that you did in some of the graded code part.

Good luck,


I had the same problem and tried the steps “restart kernal and clear outputs”… It didn’t work. With the steps in above thread you mentioned, the submission was successful! Thank you very much!

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I’m having the same issue. it is running for weeks now. I tried everything
I don’t know what to do.

There is likely an error in your code that the unit tests did not detect.

I was having the same problem, I tried both the method it suggested but they didnt work. I ultimately just rebooted (top right on the ‘(?) help’ ) the server and copied the same pieces of code I already had and this worked for me.

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For this message remember that you need to reset “N = 2” in the block where you inspected the input data example images.


That refers to this instruction: