500 when converting to html with TOC

[DawnEve]

Describe the bug
500 when converting to html with TOC

To Reproduce

1. click File - Download as - HTML, it's OK.
2. click File - Download as - HTML with toc, it's NOT OK.

Expected behavior
No file download, but a new page with large text:

500 : Internal Server Error
The error was:
nbconvert failed: toc2

Screenshots

Desktop (please complete the following information):

• OS: Ubuntu 20.04.3 LTS (GNU/Linux 5.4.0-85-generic x86_64) as a server.
• Browser [chrome] Google Chrome | 91.0.4472.164, as a client on my working PC (windows10).

# on Ubuntu
!pip3 list | grep -i nbconvert
nbconvert                         6.2.0

!pip3 list | grep -i jupyter
jupyter                           1.0.0
jupyter-client                    7.0.6
jupyter-console                   6.4.0
jupyter-contrib-core              0.3.3
jupyter-contrib-nbextensions      0.5.1
jupyter-core                      4.9.1
jupyter-highlight-selected-word   0.2.0
jupyter-latex-envs                1.4.6
jupyter-nbextensions-configurator 0.4.1
jupyter-server                    1.11.1
jupyterlab                        3.2.1
jupyterlab-pygments               0.1.2
jupyterlab-server                 2.8.2
jupyterlab-widgets                1.0.2

Additional context
When using an old version of Jupyter notebook on my win10 PC, I can download HTML with toc.

# on win10
!pip3 list | find "nbconvert"
nbconvert                         5.3.1

!pip3 list | find "jupyter"
jupyter                           1.0.0
jupyter-client                    5.2.3
jupyter-console                   5.2.0
jupyter-contrib-core              0.3.3
jupyter-contrib-nbextensions      0.5.1
jupyter-core                      4.4.0
jupyter-highlight-selected-word   0.2.0
jupyter-latex-envs                1.4.6
jupyter-nbextensions-configurator 0.4.1

Someone on sf suggest using old version of nbconvert, I haven't tried.

[christianbrodbeck]

I have the same issue (on macOS), the server console prints the following. Looks like a template file is missing?

[E 18:14:14.821 NotebookApp] nbconvert failed: toc2
    Traceback (most recent call last):
      File "/Users/christian/anaconda3/envs/mne1/lib/python3.9/site-packages/notebook/nbconvert/handlers.py", line 129, in get
        output, resources = exporter.from_notebook_node(
      File "/Users/christian/anaconda3/envs/mne1/lib/python3.9/site-packages/nbconvert/exporters/html.py", line 223, in from_notebook_node
        return super().from_notebook_node(nb, resources, **kw)
      File "/Users/christian/anaconda3/envs/mne1/lib/python3.9/site-packages/nbconvert/exporters/templateexporter.py", line 401, in from_notebook_node
        output = self.template.render(nb=nb_copy, resources=resources)
      File "/Users/christian/anaconda3/envs/mne1/lib/python3.9/site-packages/nbconvert/exporters/templateexporter.py", line 157, in template
        self._template_cached = self._load_template()
      File "/Users/christian/anaconda3/envs/mne1/lib/python3.9/site-packages/nbconvert/exporters/templateexporter.py", line 371, in _load_template
        return self.environment.get_template(template_file)
      File "/Users/christian/anaconda3/envs/mne1/lib/python3.9/site-packages/jinja2/environment.py", line 1000, in get_template
        return self._load_template(name, globals)
      File "/Users/christian/anaconda3/envs/mne1/lib/python3.9/site-packages/jinja2/environment.py", line 959, in _load_template
        template = self.loader.load(self, name, self.make_globals(globals))
      File "/Users/christian/anaconda3/envs/mne1/lib/python3.9/site-packages/jinja2/loaders.py", line 571, in load
        raise TemplateNotFound(name)
    jinja2.exceptions.TemplateNotFound: toc2
[W 18:14:14.825 NotebookApp] 500 GET /nbconvert/html_toc/Code/Yasmeen%20Aphasia/pipeline/Words-fROI.ipynb?download=true (::1): nbconvert failed: toc2
[E 18:14:14.826 NotebookApp] {
      "Host": "localhost:8888",
      "Accept": "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8",
      "Referer": "http://localhost:8888/notebooks/Code/Yasmeen%20Aphasia/pipeline/Words-fROI.ipynb",
      "User-Agent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/16.1 Safari/605.1.15"
    }
[E 18:14:14.826 NotebookApp] 500 GET /nbconvert/html_toc/Code/Yasmeen%20Aphasia/pipeline/Words-fROI.ipynb?download=true (::1) 1001.580000ms referer=http://localhost:8888/notebooks/Code/Yasmeen%20Aphasia/pipeline/Words-fROI.ipynb

Environment info:

% conda list nbconvert
# packages in environment at /Users/christian/anaconda3/envs/mne1:
#
# Name                    Version                   Build  Channel
nbconvert                 7.2.5              pyhd8ed1ab_0    conda-forge
nbconvert-core            7.2.5              pyhd8ed1ab_0    conda-forge
nbconvert-pandoc          7.2.5              pyhd8ed1ab_0    conda-forge

% conda list 'jupyter*'
# packages in environment at /Users/christian/anaconda3/envs/mne1:
#
# Name                    Version                   Build  Channel
jupyter                   1.0.0            py39h6e9494a_7    conda-forge
jupyter_client            7.4.7              pyhd8ed1ab_0    conda-forge
jupyter_console           6.4.4              pyhd8ed1ab_0    conda-forge
jupyter_contrib_core      0.4.0              pyhd8ed1ab_0    conda-forge
jupyter_contrib_nbextensions 0.5.1              pyhd8ed1ab_2    conda-forge
jupyter_core              5.0.0            py39h6e9494a_0    conda-forge
jupyter_highlight_selected_word 0.2.0           py39h6e9494a_1005    conda-forge
jupyter_latex_envs        1.4.6           pyhd8ed1ab_1002    conda-forge
jupyter_nbextensions_configurator 0.4.1              pyhd8ed1ab_2    conda-forge
jupyter_server            1.23.2             pyhd8ed1ab_0    conda-forge
jupyterlab                3.5.0              pyhd8ed1ab_0    conda-forge
jupyterlab_pygments       0.2.2              pyhd8ed1ab_0    conda-forge
jupyterlab_server         2.16.3             pyhd8ed1ab_0    conda-forge
jupyterlab_widgets        3.0.3              pyhd8ed1ab_0    conda-forge
jupytext                  1.14.0             pyheef035f_0    conda-forge

[ehsong]

Has this been solved yet? I have the same issue.