AttributeError in url_path_join() when saving notebook

[marcelo-rf]

Description

What steps will reproduce the problem?

Issue reporter is pulled up when I try to save any Jupyter notebook using Anaconda 3, Spyder 4, Python 3.7.3, and the Kite plugin

Traceback

  File "M:\Users\Marcelo\Anaconda3\lib\site-packages\spyder_notebook\widgets\notebooktabwidget.py", line 214, in close_client
    client.shutdown_kernel()
  File "M:\Users\Marcelo\Anaconda3\lib\site-packages\spyder_notebook\widgets\client.py", line 312, in shutdown_kernel
    kernel_id = self.get_kernel_id()
  File "M:\Users\Marcelo\Anaconda3\lib\site-packages\spyder_notebook\widgets\client.py", line 281, in get_kernel_id
    sessions_url = self.get_session_url()
  File "M:\Users\Marcelo\Anaconda3\lib\site-packages\spyder_notebook\widgets\client.py", line 272, in get_session_url
    return self.add_token(url_path_join(self.server_url, 'api/sessions'))
  File "M:\Users\Marcelo\Anaconda3\lib\site-packages\notebook\utils.py", line 50, in url_path_join
    initial = pieces[0].startswith('/')
AttributeError: 'NoneType' object has no attribute 'startswith'

Versions

• Spyder version: 4.1.4
• Python version: 3.7.3
• Qt version: 5.12.9
• PyQt5 version: 5.12.3
• Operating System: Windows 10

Dependencies

# Mandatory:
atomicwrites >=1.2.0           :  1.4.0 (OK)
chardet >=2.0.0                :  3.0.4 (OK)
cloudpickle >=0.5.0            :  1.5.0 (OK)
diff_match_patch >=20181111    :  20200713 (OK)
intervaltree                   :  None (OK)
IPython >=4.0                  :  7.17.0 (OK)
jedi =0.17.1                   :  0.17.1 (OK)
nbconvert >=4.0                :  5.6.1 (OK)
numpydoc >=0.6.0               :  1.1.0 (OK)
paramiko >=2.4.0               :  2.7.1 (OK)
parso =0.7.0                   :  0.7.0 (OK)
pexpect >=4.4.0                :  4.8.0 (OK)
pickleshare >=0.4              :  0.7.5 (OK)
psutil >=5.3                   :  5.7.0 (OK)
pygments >=2.0                 :  2.6.1 (OK)
pylint >=1.0                   :  2.5.3 (OK)
pyls >=0.34.0;<1.0.0           :  0.34.1 (OK)
qdarkstyle >=2.8               :  2.8.1 (OK)
qtawesome >=0.5.7              :  0.7.2 (OK)
qtconsole >=4.6.0              :  4.7.5 (OK)
qtpy >=1.5.0                   :  1.9.0 (OK)
rtree >=0.8.3                  :  0.9.4 (OK)
sphinx >=0.6.6                 :  3.2.0 (OK)
spyder_kernels >=1.9.2;<1.10.0 :  1.9.3 (OK)
watchdog                       :  None (OK)
zmq >=17                       :  19.0.1 (OK)

# Optional:
cython >=0.21                  :  0.29.21 (OK)
matplotlib >=2.0.0             :  3.2.2 (OK)
numpy >=1.7                    :  1.19.1 (OK)
pandas >=0.13.1                :  1.1.0 (OK)
scipy >=0.17.0                 :  1.5.0 (OK)
sympy >=0.7.3                  :  1.6.1 (OK)

# Spyder plugins:
spyder_notebook                :  0.3.0 (OK)

[jitseniesen]

@marcelo-rf Thanks for your report. Did Spyder actually save the notebook? Does this problem persist after a restart?

[marcelo-rf]

Hi @jitseniesen, thanks for the quick response. Yes, Spyder did save the notebook. And I had tried to restart Spyder before trying again.

I tried it again today and, for some reason, I was able to save the notebook and run it without any issues.

I am sorry, but I have no idea what has changed since I last tried.

[jitseniesen]

Thanks, I am happy to hear that the notebook was in fact saved. I think it is safe to ignore the error; I will change the plugin so that the issue reporter does not come up.