Jupyter Notebook - 500 Internal Server Error handling

I'm having trouble opening my jupyter notebooks. Everytime i do so, i get 500 internal server error. I tried to update jupyter in anaconda cmd, but it didn't work as well.

None of my notebooks work. Yesterday there was no issue. Do you have any suggestion on what is causing the problem?

Please note that updating to Notebook 7 might break some of your extensions.

[I 11:11:50.993 NotebookApp] [jupyter_nbextensions_configurator] enabled 0.6.1
[W 2023-05-06 11:11:51.391 LabApp] 'notebook_dir' has moved from NotebookApp to ServerApp. This config will be passed to ServerApp. Be sure to update your config before our next release.
[W 2023-05-06 11:11:51.391 LabApp] 'notebook_dir' has moved from NotebookApp to ServerApp. This config will be passed to ServerApp. Be sure to update your config before our next release.
[I 2023-05-06 11:11:51.391 LabApp] JupyterLab extension loaded from C:\Users\wurjasz\Anaconda3\lib\site-packages\jupyterlab
[I 2023-05-06 11:11:51.391 LabApp] JupyterLab application directory is C:\Users\wurjasz\Anaconda3\share\jupyter\lab
[I 11:11:52.459 NotebookApp] Serving notebooks from local directory: C:\Users\wurjasz
[I 11:11:52.459 NotebookApp] Jupyter Notebook 6.5.4 is running at:
[I 11:11:52.459 NotebookApp] http://localhost:8888/?token=1594dde001a3f2b96d30ba4b0439d93b41d88d1ab7d73928
[I 11:11:52.459 NotebookApp]  or http://127.0.0.1:8888/?token=1594dde001a3f2b96d30ba4b0439d93b41d88d1ab7d73928
[I 11:11:52.459 NotebookApp] Use Control-C to stop this server and shut down all kernels (twice to skip confirmation).
[C 11:11:52.491 NotebookApp]

    To access the notebook, open this file in a browser:
        file:///C:/Users/wurjasz/AppData/Roaming/jupyter/runtime/nbserver-4204-open.html
    Or copy and paste one of these URLs:
        http://localhost:8888/?token=1594dde001a3f2b96d30ba4b0439d93b41d88d1ab7d73928
     or http://127.0.0.1:8888/?token=1594dde001a3f2b96d30ba4b0439d93b41d88d1ab7d73928
[E 11:12:05.153 NotebookApp] Uncaught exception GET /notebooks/Jupyter/JupyterReportIntegration/Pivoty_Grafy.ipynb (::1)
    HTTPServerRequest(protocol='http', host='localhost:8888', method='GET', uri='/notebooks/Jupyter/JupyterReportIntegration/Pivoty_Grafy.ipynb', version='HTTP/1.1', remote_ip='::1')
    Traceback (most recent call last):
      File "C:\Users\wurjasz\Anaconda3\lib\site-packages\tornado\web.py", line 1713, in _execute
        result = await result
      File "C:\Users\wurjasz\Anaconda3\lib\site-packages\tornado\gen.py", line 782, in run
        yielded = self.gen.send(value)
      File "C:\Users\wurjasz\Anaconda3\lib\site-packages\notebook\notebook\handlers.py", line 94, in get
        self.write(self.render_template('notebook.html',
      File "C:\Users\wurjasz\Anaconda3\lib\site-packages\notebook\base\handlers.py", line 515, in render_template
        return template.render(**ns)
      File "C:\Users\wurjasz\Anaconda3\lib\site-packages\jinja2\environment.py", line 1301, in render
        self.environment.handle_exception()
      File "C:\Users\wurjasz\Anaconda3\lib\site-packages\jinja2\environment.py", line 936, in handle_exception
        raise rewrite_traceback_stack(source=source)
      File "C:\Users\wurjasz\Anaconda3\lib\site-packages\notebook\templates\notebook.html", line 1, in top-level template code
        {% extends "page.html" %}
      File "C:\Users\wurjasz\Anaconda3\lib\site-packages\notebook\templates\page.html", line 187, in top-level template code
        {% block header %}
      File "C:\Users\wurjasz\Anaconda3\lib\site-packages\notebook\templates\notebook.html", line 115, in block 'header'
        {% for exporter in get_frontend_exporters() %}
      File "C:\Users\wurjasz\Anaconda3\lib\site-packages\notebook\notebook\handlers.py", line 23, in get_frontend_exporters
        from nbconvert.exporters.base import get_export_names, get_exporter
      File "C:\Users\wurjasz\Anaconda3\lib\site-packages\nbconvert\__init__.py", line 3, in <module>
        from . import filters, postprocessors, preprocessors, writers
      File "C:\Users\wurjasz\Anaconda3\lib\site-packages\nbconvert\filters\__init__.py", line 8, in <module>
        from .markdown import *
      File "C:\Users\wurjasz\Anaconda3\lib\site-packages\nbconvert\filters\markdown.py", line 13, in <module>
        from .markdown_mistune import markdown2html_mistune
      File "C:\Users\wurjasz\Anaconda3\lib\site-packages\nbconvert\filters\markdown_mistune.py", line 37, in <module>
        class MathBlockGrammar(mistune.BlockGrammar):
    AttributeError: module 'mistune' has no attribute 'BlockGrammar'
[E 11:12:05.173 NotebookApp] {
      "Host": "localhost:8888",
      "Accept": "text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.7",
      "Referer": "http://localhost:8888/tree/Jupyter/JupyterReportIntegration",
      "User-Agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/113.0.0.0 Safari/537.36"
    }
[E 11:12:05.174 NotebookApp] 500 GET /notebooks/Jupyter/JupyterReportIntegration/Pivoty_Grafy.ipynb (::1) 251.680000ms referer=http://localhost:8888/tree/Jupyter/JupyterReportIntegration

Below command solved the issue.

conda install -c conda-forge nbconvert mistune

Please downgrade your anaconda navigator to 2.3.1.

A lot of people are facing this issue

https://github.com/jupyter/nbconvert/issues/1864

From the link posted above:

conda install -c conda-forge 'nbconvert>=7' 'mistune>=2`