title: jupyter notebooks problem loading nbextensions
body: <p>I have installed Anaconda3 5.0.1 for windows. Afterwards, I installed nbextensions for Jupyter notebook.</p>
  
  <p>I have used following code in Anaconda Prompt for nbextension installation:
  pip install jupyter_contrib_nbextensions
  jupyter-contrib nbextension install</p>
  
  <p>When i open Jupyter notebook and click on NBextensions tab, I see the following error and no extensions are added to my notebooks.</p>
  
  <pre><code>Snap! Failed to load config section "notebook"
  Internal Server Error
  </code></pre>
  
  <pre><code>Traceback (most recent call last):
    File "C:\Users\Efseaff\Anaconda3\lib\site-packages\notebook\base\handlers.py", line 516, in wrapper
      result = yield gen.maybe_future(method(self, *args, **kwargs))
    File "C:\Users\Efseaff\Anaconda3\lib\site-packages\tornado\web.py", line 2898, in wrapper
      return method(self, *args, **kwargs)
    File "C:\Users\Efseaff\Anaconda3\lib\site-packages\notebook\services\config\handlers.py", line 20, in get
      self.finish(json.dumps(self.config_manager.get(section_name)))
    File "C:\Users\Efseaff\Anaconda3\lib\site-packages\notebook\services\config\manager.py", line 25, in get
      recursive_update(config, cm.get(section_name))
    File "C:\Users\Efseaff\Anaconda3\lib\site-packages\traitlets\config\manager.py", line 63, in get
      return json.load(f)
    File "C:\Users\Efseaff\Anaconda3\lib\json\__init__.py", line 299, in load
      parse_constant=parse_constant, object_pairs_hook=object_pairs_hook, **kw)
    File "C:\Users\Efseaff\Anaconda3\lib\json\__init__.py", line 354, in loads
      return _default_decoder.decode(s)
    File "C:\Users\Efseaff\Anaconda3\lib\json\decoder.py", line 339, in decode
      obj, end = self.raw_decode(s, idx=_w(s, 0).end())
    File "C:\Users\Efseaff\Anaconda3\lib\json\decoder.py", line 355, in raw_decode
      obj, end = self.scan_once(s, idx)
  json.decoder.JSONDecodeError: Expecting ',' delimiter: line 5 column 3 (char 72)
  </code></pre>
  
  <p>In a related question on Github - <a href="https://github.com/ipython-contrib/jupyter_contrib_nbextensions/issues/1295" rel="nofollow noreferrer">https://github.com/ipython-contrib/jupyter_contrib_nbextensions/issues/1295</a> - the questioner is directed to check their Failed JSON file : C:\Users\ ... \nbconfig\notebook.json in <a href="https://jsonlint.com/" rel="nofollow noreferrer">https://jsonlint.com/</a></p>
  
  <p>My C:...\notebook.json file is:</p>
  
  <pre><code>{
    "load_extensions": {
      "jupyter-js-widgets/extension": true
    }
    "CodeCell": {
      "cm_config": {
        "autoCloseBrackets": false,
        "cursorBlinkRate": 0
      }
    } 
  }
  </code></pre>
  
  <p>The output of <a href="https://jsonlint.com/" rel="nofollow noreferrer">https://jsonlint.com/</a> is:</p>
  
  <pre><code>Error: Parse error on line 4:
  ...xtension": true  }   "CodeCell": {       "cm_
  ---------------------^
  Expecting 'EOF', '}', ',', ']', got 'STRING'
  </code></pre>
  
  <p>Please help me fix this file</p>
  
  <p><em>SOLVED</em></p>
  
  <p>The steps on <a href="https://jupyter-contrib-nbextensions.readthedocs.io/en/latest/install.html#install-javascript-and-css-files" rel="nofollow noreferrer">https://jupyter-contrib-nbextensions.readthedocs.io/en/latest/install.html#install-javascript-and-css-files</a> don't explicitly show to configure them with:
  <code>pip install jupyter_nbextensions_configurator</code> and
  <code>jupyter nbextensions_configurator enable --system</code>
  I found them ... elsewhere.</p>