UnicodeEncodeError: 'ascii' codec can't encode character u'\xd7'

[mwouts]

Extract of jupyter notebook logs:

Pre-save hook failed on notebook.Rmd
Traceback (most recent call last):
(...)      
      File "nbrmd/nbrmd.py", line 381, in writef
        nbformat.write(nb, fp)
      File "nbformat/__init__.py", line 169, in write
        fp.write(s)
    UnicodeEncodeError: 'ascii' codec can't encode character u'\xd7' in position 14653: ordinal not in range(128)