title: Kernel error: jupyter_client/connect.py AssertionError
body: <h2>Error message</h2>
  
  <pre><code>Traceback (most recent call last):
        File "/home/djan/anaconda3/lib/python3.7/site-packages/tornado/web.py", line 1699, in _execute
          result = await result
        File "/home/djan/anaconda3/lib/python3.7/site-packages/tornado/gen.py", line 742, in run
          yielded = self.gen.throw(*exc_info)  # type: ignore
        File "/home/djan/anaconda3/lib/python3.7/site-packages/notebook/services/sessions/handlers.py", line 72, in post
          type=mtype))
        File "/home/djan/anaconda3/lib/python3.7/site-packages/tornado/gen.py", line 735, in run
          value = future.result()
        File "/home/djan/anaconda3/lib/python3.7/site-packages/tornado/gen.py", line 742, in run
          yielded = self.gen.throw(*exc_info)  # type: ignore
        File "/home/djan/anaconda3/lib/python3.7/site-packages/notebook/services/sessions/sessionmanager.py", line 88, in create_session
          kernel_id = yield self.start_kernel_for_session(session_id, path, name, type, kernel_name)
        File "/home/djan/anaconda3/lib/python3.7/site-packages/tornado/gen.py", line 735, in run
          value = future.result()
        File "/home/djan/anaconda3/lib/python3.7/site-packages/tornado/gen.py", line 742, in run
          yielded = self.gen.throw(*exc_info)  # type: ignore
        File "/home/djan/anaconda3/lib/python3.7/site-packages/notebook/services/sessions/sessionmanager.py", line 101, in start_kernel_for_session
          self.kernel_manager.start_kernel(path=kernel_path, kernel_name=kernel_name)
        File "/home/djan/anaconda3/lib/python3.7/site-packages/tornado/gen.py", line 735, in run
          value = future.result()
        File "/home/djan/anaconda3/lib/python3.7/site-packages/tornado/gen.py", line 209, in wrapper
          yielded = next(result)
        File "/home/djan/anaconda3/lib/python3.7/site-packages/notebook/services/kernels/kernelmanager.py", line 168, in start_kernel
          super(MappingKernelManager, self).start_kernel(**kwargs)
        File "/home/djan/anaconda3/lib/python3.7/site-packages/jupyter_client/multikernelmanager.py", line 110, in start_kernel
          km.start_kernel(**kwargs)
        File "/home/djan/anaconda3/lib/python3.7/site-packages/jupyter_client/manager.py", line 240, in start_kernel
          self.write_connection_file()
        File "/home/djan/anaconda3/lib/python3.7/site-packages/jupyter_client/connect.py", line 547, in write_connection_file
          kernel_name=self.kernel_name
        File "/home/djan/anaconda3/lib/python3.7/site-packages/jupyter_client/connect.py", line 212, in write_connection_file
          with secure_write(fname) as f:
        File "/home/djan/anaconda3/lib/python3.7/contextlib.py", line 112, in __enter__
          return next(self.gen)
        File "/home/djan/anaconda3/lib/python3.7/site-packages/jupyter_client/connect.py", line 105, in secure_write
          assert '0600' == oct(stat.S_IMODE(os.stat(fname).st_mode)).replace('0o', '0')
      AssertionError
  </code></pre>
  
  <h2>System information</h2>
  
  <p>Running Jupyter (v. 1.0.0) on a Linux server, with anaconda3 (v. 2019.07) 64-bit.</p>
  
  <h2>Available Kernels</h2>
  
  <p>Available kernels:<br>
  &nbsp;&nbsp; python3 &nbsp;&nbsp; /home/djan/.local/share/jupyter/kernels/python3<br>
  &nbsp;&nbsp; nn &nbsp;&nbsp;&nbsp;&nbsp; /home/djan/.local/share/jupyter/kernels/nn  </p>
  
  <h2>Reproducing the issue</h2>
  
  <ol>
  <li>Install the newest anaconda3 version.</li>
  <li>Run Jupyter notebook in the base version --> Kernel runs fine</li>
  <li>Create a new environment with python: <code>conda create -n test python=3.7</code></li>
  <li>After activating the environment, Jupyter notebook is not available, thus I must install it via Conda: <code>conda install -c anaconda jupyter</code></li>
  <li>Run Jupyter notebook in the test environment --> Kernel breaks down as explained above</li>
  </ol>
  
  <h2>What I tried so far</h2>
  
  <p>There seems to be an issue with file permissions when running Jupyter on a server inside a Conda environment. I tried to give all files inside my anaconda3 folder the requested permissions (0600), but this did not help.</p>