Error in console with message `Matplotlib is building the font cache; this may take a moment.`

[audreyc38]

Description

What steps will reproduce the problem?

Hello, I recently updated Spyder using Anaconda and insde the iPython console I keep getting the following error:
"An error occured while starting the kernel
Matplotlib is building the font cache; this may take a moment."

The console has not been available to me since I updated Spyder several days ago (I have given it many "moments" to build the font cache) and I'm not sure how to resolve.

I launch Spyder using my Terminal.

Versions

• Spyder version: 6.0.3 (conda)
• Python version: 3.9.18 64-bit
• Qt version: 5.15.2
• PyQt5 version: 5.15.10
• Operating System: Linux-6.5.0-26-generic-x86_64-with-glibc2.35

Dependencies

# Mandatory:
aiohttp >=3.9.3                  :  3.11.10 (OK)
asyncssh >=2.14.0,<3.0.0         :  2.17.0 (OK)
atomicwrites >=1.2.0             :  1.4.1 (OK)
chardet >=2.0.0                  :  4.0.0 (OK)
cloudpickle >=0.5.0              :  3.0.0 (OK)
cookiecutter >=1.6.0             :  2.6.0 (OK)
diff_match_patch >=20181111      :  20230430 (OK)
github >=2.3.0                   :  2.4.0 (OK)
importlib_metadata >=4.6.0       :  8.5.0 (OK)
intervaltree >=3.0.2             :  3.1.0 (OK)
IPython >=8.13.0,<9.0.0,!=8.17.1 :  8.15.0 (OK)
jedi >=0.17.2,<0.20.0            :  0.19.2 (OK)
jellyfish >=0.7                  :  1.1.3 (OK)
jsonschema >=3.2.0               :  4.23.0 (OK)
keyring >=17.0.0                 :  24.3.1 (OK)
nbconvert >=4.0                  :  7.16.6 (OK)
numpydoc >=0.6.0                 :  1.7.0 (OK)
parso >=0.7.0,<0.9.0             :  0.8.4 (OK)
pexpect >=4.4.0                  :  4.8.0 (OK)
pickleshare >=0.4                :  0.7.5 (OK)
psutil >=5.3                     :  5.9.0 (OK)
pygments >=2.0                   :  2.15.1 (OK)
pylint >=3.1,<4                  :  3.3.5 (OK)
pylint_venv >=3.0.2              :  3.0.3 (OK)
pyls_spyder >=0.4.0              :  0.4.0 (OK)
pylsp >=1.12.0,<1.13.0           :  1.12.2 (OK)
pylsp_black >=2.0.0,<3.0.0       :  2.0.0 (OK)
pyuca >=1.2                      :  1.2 (OK)
qdarkstyle >=3.2.0,<3.3.0        :  3.2.3 (OK)
qstylizer >=0.2.2                :  0.2.2 (OK)
qtawesome >=1.3.1,<1.4.0         :  1.3.1 (OK)
qtconsole >=5.6.1,<5.7.0         :  5.6.1 (OK)
qtpy >=2.4.0                     :  2.4.1 (OK)
rtree >=0.9.7                    :  1.1.0 (OK)
setuptools >=49.6.0              :  75.8.0 (OK)
sphinx >=0.6.6                   :  7.3.7 (OK)
spyder_kernels >=3.0.2,<3.1.0    :  3.0.2 (OK)
superqt >=0.6.2,<1.0.0           :  0.6.7 (OK)
textdistance >=4.2.0             :  4.6.2 (OK)
three_merge >=0.1.1              :  0.1.1 (OK)
watchdog >=0.10.3                :  4.0.2 (OK)
xdg >=0.26                       :  0.28 (OK)
yarl >=1.9.4                     :  1.18.0 (OK)
zmq >=24.0.0                     :  26.2.0 (OK)

# Optional:
cython >=0.21                    :  None (NOK)
matplotlib >=3.0.0               :  3.9.2 (OK)
numpy >=1.7                      :  1.26.4 (OK)
pandas >=1.1.1                   :  2.2.3 (OK)
scipy >=0.17.0                   :  1.13.1 (OK)
sympy >=0.7.3                    :  None (NOK)

[ccordoba12]

Hey @audreyc38, thanks for reporting. You said:

The console has not been available to me since I updated Spyder several days ago (I have given it many "moments" to build the font cache) and I'm not sure how to resolve.

Does this happen to you for any console you open or only for the first one?

In any case, we'll fix this error in our next version (6.0.6) and instruct you on how to fix it in the meantime.

[ccordoba12]

@jsbautista, to fix this please add the string Matplotlib is building the font cache to the list of benign messages in ipythonconsole/widgets/client.py, with a comment that references this issue.

[audreyc38]

Hey @audreyc38, thanks for reporting. You said:

The console has not been available to me since I updated Spyder several days ago (I have given it many "moments" to build the font cache) and I'm not sure how to resolve.

Does this happen to you for any console you open or only for the first one?

In any case, we'll fix this error in our next version (6.0.6) and instruct you on how to fix it in the meantime.

Thanks for the quick response! It occurs for every console.

[ccordoba12]

Thanks for checking that @audreyc38. Now we need your help to confirm if the solution we have in mind really fixes this problem.

For that, you need to:

• Open a terminal (gnome-terminal or konsole).

• Run there the command

  cd /home/<your user>/anaconda3
  

  I'm assuming you're using Anaconda, but please change that for miniconda3 or something else in case you installed Spyder differently.

• Then run the command

  spyder lib/python3.9/site-packages/spyder/plugins/ipythonconsole/widgets/client.py
  

• Find the method is_benign_error in that file.

• At the end of the benign_errors list, add the string "Matplotlib is building the font cache", as shown here.

• Close and restart Spyder.

That should let you use the IPython console again.

[audreyc38]

Thanks for checking that @audreyc38. Now we need your help to confirm if the solution we have in mind really fixes this problem.

For that, you need to:

• Open a terminal (gnome-terminal or konsole).

• Run there the command

  cd /home/<your user>/anaconda3
  

  I'm assuming you're using Anaconda, but please change that for miniconda3 or something else in case you installed Spyder differently.

• Then run the command

  spyder lib/python3.9/site-packages/spyder/plugins/ipythonconsole/widgets/client.py
  

• Find the method is_benign_error in that file.

• At the end of the benign_errors list, add the string "Matplotlib is building the font cache", as shown here.

• Close and restart Spyder.

That should let you use the IPython console again.

Thank you! This worked!!

[ccordoba12]

Great! Thanks for helping us to check that @audreyc38!

As I said, we'll fix this in our next version (6.0.6), to be released next month. So, if you update to another version less than that one in the meantime, you'll need to follow the same procedure to patch Spyder with the fix.