spyder: CommError: The comm is not connected when changing Matplotlib backend

Description

What steps will reproduce the problem?

when choosing inline backend graphics, the spyder returns an error message

Traceback

Traceback (most recent call last):
  File "C:\Users\wisam\anaconda3\envs\PEA Tabular Project\lib\site-packages\spyder\plugins\preferences\widgets\configdialog.py", line 127, in accept
    configpage.apply_changes()
  File "C:\Users\wisam\anaconda3\envs\PEA Tabular Project\lib\site-packages\spyder\plugins\preferences\api.py", line 110, in apply_changes
    self.apply_callback()
  File "C:\Users\wisam\anaconda3\envs\PEA Tabular Project\lib\site-packages\spyder\plugins\preferences\api.py", line 142, in <lambda>
    self._apply_settings_tabs(self.changed_options))
  File "C:\Users\wisam\anaconda3\envs\PEA Tabular Project\lib\site-packages\spyder\plugins\preferences\api.py", line 170, in _apply_settings_tabs
    self.apply_settings(options)
  File "C:\Users\wisam\anaconda3\envs\PEA Tabular Project\lib\site-packages\spyder\api\preferences.py", line 104, in wrapper
    func(opts)
  File "C:\Users\wisam\anaconda3\envs\PEA Tabular Project\lib\site-packages\spyder\plugins\ipythonconsole\plugin.py", line 447, in apply_plugin_settings
    for client in self.clients]
  File "C:\Users\wisam\anaconda3\envs\PEA Tabular Project\lib\site-packages\spyder\plugins\ipythonconsole\plugin.py", line 447, in <listcomp>
    for client in self.clients]
  File "C:\Users\wisam\anaconda3\envs\PEA Tabular Project\lib\site-packages\spyder\plugins\ipythonconsole\widgets\shell.py", line 343, in get_matplotlib_backend
    blocking=True).get_matplotlib_backend()
  File "C:\Users\wisam\anaconda3\envs\PEA Tabular Project\lib\site-packages\spyder_kernels\comms\commbase.py", line 550, in __call__
    raise CommError("The comm is not connected.")
spyder_kernels.comms.commbase.CommError: The comm is not connected.

Versions

• Spyder version: 5.0.0
• Python version: 3.6.13
• Qt version: 5.9.6
• PyQt5 version: 5.9.2
• 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           :  1.6.0 (OK)
cookiecutter >=1.6.0          :  1.7.2 (OK)
diff_match_patch >=20181111   :  20200713 (OK)
intervaltree >=3.0.2          :  3.1.0 (OK)
IPython >=7.6.0               :  7.16.1 (OK)
jedi =0.17.2                  :  0.17.2 (OK)
jsonschema >=3.2.0            :  3.2.0 (OK)
keyring >=17.0.0              :  22.3.0 (OK)
nbconvert >=4.0               :  6.0.7 (OK)
numpydoc >=0.6.0              :  1.1.0 (OK)
paramiko >=2.4.0              :  2.7.2 (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                  :  5.8.0 (OK)
pygments >=2.0                :  2.8.1 (OK)
pylint >=1.0                  :  2.7.4 (OK)
pyls >=0.36.2;<1.0.0          :  0.36.2 (OK)
pyls_black >=0.4.6            :  0.4.6 (OK)
pyls_spyder >=0.3.2           :  0.3.2 (OK)
qdarkstyle =3.0.2             :  3.0.2 (OK)
qstylizer >=0.1.10            :  0.1.10 (OK)
qtawesome >=0.5.7             :  1.0.2 (OK)
qtconsole >=5.0.3             :  5.0.3 (OK)
qtpy >=1.5.0                  :  1.9.0 (OK)
rtree >=0.8.3                 :  0.9.4 (OK)
setuptools >=39.0.0           :  52.0.0.post20210125 (OK)
sphinx >=0.6.6                :  3.5.3 (OK)
spyder_kernels >=2.0.1,<2.1.0 :  2.0.1 (NOK)
textdistance >=4.2.0          :  4.2.1 (OK)
three_merge >=0.1.1           :  0.1.1 (OK)
watchdog >=0.10.3;<2.0.0      :  1.0.2 (OK)
zmq >=17                      :  20.0.0 (OK)

# Optional:
cython >=0.21                 :  None (NOK)
matplotlib >=2.0.0            :  3.3.4 (OK)
numpy >=1.7                   :  1.19.5 (OK)
pandas >=1.1.1                :  1.1.5 (OK)
scipy >=0.17.0                :  1.5.2 (OK)
sympy >=0.7.3                 :  None (NOK)