Submission issue

I cannot validate the submission getting a fail as final score. Here the error

Traceback (most recent call last):
File “/opt/conda/lib/python3.7/site-packages/nbgrader/server_extensions/validate_assignment/”, line 46, in validate_notebook
result = validator.validate(fullpath)
File “/opt/conda/lib/python3.7/site-packages/nbgrader/”, line 311, in validate
nb = self._preprocess(nb)
File “/opt/conda/lib/python3.7/site-packages/nbgrader/”, line 290, in _preprocess
nb, resources = pp.preprocess(nb, resources)
File “/opt/conda/lib/python3.7/site-packages/nbgrader/preprocessors/”, line 16, in preprocess
raise ValidationError(msg)
jsonschema.exceptions.ValidationError: Notebook failed to validate; the nbgrader metadata may be corrupted

Any help?

It looks like your notebook is damaged somehow: some of the info for the grader (which you can’t normally even see when you run the notebook) is either missing or changed in an invalid way. Did you edit it using some tool other than the Course website?

In any case, you’ll need to get a fresh copy and then carefully “copy/paste” over just your completed work in the “YOUR CODE HERE” sections. There are instructions on the DLS FAQ Thread for how to get the clean copy.

Also note that using the “Validate” button is not equivalent to getting the notebook graded. It just runs the test cases in the notebook. You are better off just doing “Cell → Run All” and then looking through the notebook and checking all the results. Then click “Submit Assignment”.