There seems to be a new bug in Nikola when building Jupyter notebook pages and using the latest version of nbconvert. [This is the Jupyter library that converts the *.ipynb files to html.]
When I install nbconvert==5.5, it works fine. When I install 6.0, released in September, I get this exception:
jinja2.exceptions.TemplateNotFound: basic.tpl
That file basic.tpl is found here in the 5.5 installation:
./nbconvert/templates/html/basic.tpl
It is missing from the 6.0 installation. In fact, that templates directory is basically empty. It seems the latest release made significant changes to the template system. From looking at the github issues for nbconvert, it seems other people are experiencing this issue also.
-Jim