I resolved it now. It wasn’t anything in my code or anything corrupted in the notebook. The issue was that the “optional exercise” at the bottom of the note book (“6 - Tuning hidden layer size (optional/ungraded exercise”) was taking a bit of time to run, which failed the grader for some reason… (it does not involve any code I added, the notebook just contains a cell that is optional to run).
I removed 20 and 50 from the hidden_layer_sizes = [1, 2, 3, 4, 5, 20, 50] and submitted again, and it resolved the issue.
Here’s a screenshot of the relevant cell in case you want to fix this problem:
(the cell originally had 20 and 50 in hidden_layer_sizes = [1, 2, 3, 4, 5, 20, 50]).
Tal