500 Internal Server Error with latest Tornado

[scribby182]

Built a new conda environment today and found Jupyter Notebooks unable to load notebooks. Clicking a notebook yielded a 500 Internal server error. I believe the relevant error in the console was: " AttributeError: module 'tornado.web' has no attribute 'asynchronous'"

Seemed to coincide with either recent notebook version release or tornado version release. Fixed temporarily by:

    pip uninstall tornado
    pip install tornado=5.1.1

[david-waterworth]

I think this has been fixed, tornado 6.x had a compatibility issue with notebooks

#4311 (comment)

[scribby182]

Good call. Updating nbconvert fixed things.

Strangely I had to do it twice. First time said it updated, but then still showed 5.3.1 in pip list. Second time actually stuck.