Plotly team fixed this issue. You have to update nbformat to 4.3.0.
conda install -c anaconda nbformat
updated nbformat to this version, but
conda install -c conda-forge nbformat
installs/updates only version 4.2.0
Plotly team fixed this issue. You have to update nbformat to 4.3.0.
conda install -c anaconda nbformat
updated nbformat to this version, but
conda install -c conda-forge nbformat
installs/updates only version 4.2.0