nbconvert version 6.0.0 breaks nbgrader feedback

[echuber2]

Basically, nbconvert version 6.0.0 breaks nbgrader's generate_feedback. Need to pin nbconvert to 5.6.1 for now for compatibility.

nbgrader --version

Python version 3.8.5 | packaged by conda-forge | (default, Aug 29 2020, 01:22:49)
[GCC 7.5.0]
nbgrader version 0.6.1

jupyter notebook --version

6.1.3

Expected behavior

Should be able to run generate_feedback

Actual behavior

Can't run generate_feedback -- incompatibility with HTMLExporter from latest nbconvert (versions 6 and later)

Downgrading nbconvert to 5.6.1 resolves the issue.

Steps to reproduce the behavior

Try using generate_feedback with nbconvert 6.0.0 or later installed. Note that these were in pre-release until just yesterday.

[echuber2]

Note: template system "completely revamped" https://nbconvert.readthedocs.io/en/latest/architecture.html#templates

[BertR]

Thanks for reporting this @echuber2