[Bug]: Using an ipython config of `InteractiveShellApp.matplotlib='inline'` fails on macos for `matplotlib>3.9.0` · Issue #28855 · matplotlib/matplotlib · GitHub

Bug summary

I am using a Jupyter notebook in VS Code Version: 1.93.1. on MacOS Ventura 13.4.1 and Python 3.12.5

With matplotlib<=3.9.0, I can plot visualizations inline within VS Code. The reported backend is by default inline and everything is fine.

Starting with version 3.9.1, the default backend apparently switched to macosx. When I try to plot something now, a new Python window pops up, but no plot is created unless I add plt.show().

Is this the intended behavior? It breaks essentially all of my notebooks because I would have to go in and add %matplotlib inline to make things work again.

Code for reproduction

import matplotlib.pyplot as plt

import matplotlib

print(matplotlib.get_backend())

plt.plot([0, 1, 2], [1, 2, 3])

Actual outcome

With matplotlib<=3.9.0:

With matplotlib>3.9.0:

Expected outcome

Default backend should be inline in matplotlib>3.9.0.

Additional information

No response

Operating system

MacOS Ventura 13.4.1

Matplotlib Version

3.9.0, 3.9.1, 3.9.2

Matplotlib Backend

inline, macosx

Python version

3.12.5

Jupyter version

6.5.1

Installation

pip

@ianthomas23 This is probably more fallout from moving the backend mappings around?

This is not intended, the default matplotib backend in JupyterLab and Notebook should still be the inline backend.

I cannot reproduce this using a new virtual environment on Sonoma 14.6.1 with Python 3.12.6, Matplotlib 3.9.2 and VSCode 1.93.1. Here's my output:

I note that for matplotlib.get_backend() you get the short name inline whereas I get the fully qualified module://matplotlib_inline.backend_inline although the former is shorthand for the latter so may not be significant. But it is a clue.

I think you are using an unusually old versions of the jupyter packages compared to latest matplotlib. ipykernel and ipython are probably the key ones. This is what I have in my new env:

$ jupyter --version
Selected Jupyter core packages...
IPython          : 8.27.0
ipykernel        : 6.29.5
ipywidgets       : 8.1.5
jupyter_client   : 8.6.3
jupyter_core     : 5.7.2
jupyter_server   : 2.14.2
jupyterlab       : 4.2.5
nbclient         : 0.10.0
nbconvert        : 7.16.4
nbformat         : 5.10.4
notebook         : 7.2.2
qtconsole        : not installed
traitlets        : 5.14.3

If by a Jupyter version of 6.5.1 you mean the version of notebook then that is from October 2022 and if you have a similar age of ipykernel and ipython I wouldn't be surprised at some strange results.

Can you do two things?

Run jupyter --version and post your output here, then we can see exactly what versions of the important packages you are using.
Create new virtual environment and install recent packages (matplotlib and notebook may be enough). I think this should work fine for you.

Thanks for engaging with this.

I created a fresh virtual environment and used it for what I described above. Here is the output of jupyter --version:

IPython          : 8.27.0
ipykernel        : 6.29.5
ipywidgets       : not installed
jupyter_client   : 8.6.3
jupyter_core     : 5.7.2
jupyter_server   : not installed
jupyterlab       : not installed
nbclient         : not installed
nbconvert        : not installed
nbformat         : not installed
notebook         : not installed
qtconsole        : not installed
traitlets        : 5.14.3

I then ran pip install notebook, and now jupyter --version reports:

Selected Jupyter core packages...
IPython          : 8.27.0
ipykernel        : 6.29.5
ipywidgets       : not installed
jupyter_client   : 8.6.3
jupyter_core     : 5.7.2
jupyter_server   : 2.14.2
jupyterlab       : 4.2.5
nbclient         : 0.10.0
nbconvert        : 7.16.4
nbformat         : 5.10.4
notebook         : 7.2.2
qtconsole        : not installed
traitlets        : 5.14.3

The error is still exactly the same, with the same reported backends.

OK, let's try removing VSCode from the workflow. Can you use jupyter lab or jupyter notebook to run the test code in a browser?

Good thinking. Here is what I did:

python3 -m venv .venv
source .venv/bin/activate
pip install jupyter ipykernel matplotlib
jupyter notebook

Notebook browser starts up
Start test notebook
Select kernel .venv (Kernel->Change Kernel...)
Run code

The reported backend is macosx, and the behavior is as described above. In addition, I am getting the following message in the ServerApp log when running the plt.plot command:

[IPKernelApp] WARNING | GUI event loop or pylab initialization failed

Downgrading to 3.9.0 also fixes the behavior, just like from within VS Code.

The warning comes from here:
https://github.com/ipython/ipython/blob/68a3854c3e582de0e29dba22f483729c01c6f38b/IPython/core/shellapp.py#L297

The next line shows a traceback, can you copy and paste that from the logs too?

Small correction: The warning appears every time the kernel is restarted.

Weirdly, there is no traceback. Here is the output from a couple of kernel restarts:

[I 2024-09-23 11:37:59.717 ServerApp] Kernel restarted: 3c53522f-3143-40d8-81ab-9ecab90c6db3
[I 2024-09-23 11:37:59.723 ServerApp] Starting buffering for 3c53522f-3143-40d8-81ab-9ecab90c6db3:23ad432f-7f8e-41ea-828e-98359f647db2
[I 2024-09-23 11:37:59.726 ServerApp] Connecting to kernel 3c53522f-3143-40d8-81ab-9ecab90c6db3.
[I 2024-09-23 11:37:59.726 ServerApp] Restoring connection for 3c53522f-3143-40d8-81ab-9ecab90c6db3:23ad432f-7f8e-41ea-828e-98359f647db2
[IPKernelApp] WARNING | GUI event loop or pylab initialization failed
[I 2024-09-23 11:38:07.787 ServerApp] Kernel restarted: 3c53522f-3143-40d8-81ab-9ecab90c6db3
[I 2024-09-23 11:38:07.794 ServerApp] Starting buffering for 3c53522f-3143-40d8-81ab-9ecab90c6db3:23ad432f-7f8e-41ea-828e-98359f647db2
[I 2024-09-23 11:38:07.797 ServerApp] Connecting to kernel 3c53522f-3143-40d8-81ab-9ecab90c6db3.
[I 2024-09-23 11:38:07.797 ServerApp] Restoring connection for 3c53522f-3143-40d8-81ab-9ecab90c6db3:23ad432f-7f8e-41ea-828e-98359f647db2
[IPKernelApp] WARNING | GUI event loop or pylab initialization failed

I am running out of ideas here.

Matplotlib 3.9.0 is about the right time for things to break with backends as there was a major refactor to move IPython's management of backends to Matplotlib where it more correctly belongs. #27948 was the PR on the Matplotlib side for this, and there were a few glitches fixed later such as #28332 and ipython/ipython#14451.

But as I cannot reproduce the problem it is somewhat difficult to understand it. What it feels like now (and I have been wrong before 😄) is that you have some overriding of the default Matplotlib backend somewhere such as an environment variable or rcParams, or some preamble code that is run when you start a kernel or notebook which does some backend setting or manipulation. There have been occasions where Jupyter extensions have done something like this (though not to Matplotlib as far as I know) and their forced changes have affected things they shouldn't.

If it was my mac, what I would try next is to create a new user who therefore doesn't have any Matplotlib or Jupyter configuration set up, create a venv for them and re-try the test.

I suppose we should also consider that although we are both using the same package versions, we are using different python installations. I'm using mamba and I guess you are using homebrew? The difference here may be important perhaps in regard to the venvs being fully isolated or not.

Oh wow, I am so sorry for having you chase this down. I found the culprit:

I remembered that a long time ago I wanted the default figure format to be SVG, so I created a file ~/.ipython/profile_default/ipython_kernel_config.py and put the following in it:

c.InteractiveShellApp.matplotlib = 'inline'
c.InlineBackend.figure_formats = {'svg'}

I removed it just now, and everything works as expected with >3.9.0!

Again, so sorry for this coming back to "user error".

I am curious, though, if you know why this breaks after 3.9.0, and if you had a different suggestion to globally make SVG the default format?

I am glad we have found the actual bug. It is a bug, it should still work but it is an unusual thing to do as the methods of rendering that support the inline backend already have it as their default, so it should essentially be a no-op.

It will need fixing, but isn't urgent as this is definitely a corner case. I will change the title of this issue to reflect what the problem really is.

I don't have any suggestions for making SVG the default. I would never do that as there are some things that SVG does not render well such as some color gradients. And I pretty much always use the ipympl backend rather than inline as it is interactive.

It does make sense to use rcParams._get if backend selection is to be avoided. I'm just uncertain how IPython integration will be enabled if https://github.com/ipython/matplotlib-inline/blob/90034cf74d7e5a6dea54b9d8f148427450354c45/matplotlib_inline/backend_inline.py#L214 sees the 'unset-backend' sentinel value at import time (and there appear to be no other callers.) I suppose this is something to figure out in matplotlib-inline for the (potential) PR?

@QuLogic Thanks, I will try the rcParams._get in matplotlib-inline. I'll need to do some comprehensive manual testing to clarify in ipython integration is affected by this.

Just noting here that there was a PR at least partially addressing this over in ipython/matplotlib-inline#38

Is there any further action to take in this repo, or should this be closed out here?

I think this is handled on the maptoltlib-inline side. Closing for now, please ping to re-open if I am confused.

[Bug]: Using an ipython config of `InteractiveShellApp.matplotlib='inline'` fails on macos for `matplotlib>3.9.0` · Issue #28855 · matplotlib/matplotlib · GitHub

[Bug]: Using an ipython config of InteractiveShellApp.matplotlib='inline' fails on macos for matplotlib>3.9.0 #28855

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Additional information

Operating system

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Matplotlib Backend

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Installation

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[Bug]: Using an ipython config of `InteractiveShellApp.matplotlib='inline'` fails on macos for `matplotlib>3.9.0` · Issue #28855 · matplotlib/matplotlib · GitHub

[Bug]: Using an ipython config of InteractiveShellApp.matplotlib='inline' fails on macos for matplotlib>3.9.0 #28855

Description

Bug summary

Code for reproduction

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Expected outcome

Additional information

Operating system

Matplotlib Version

Matplotlib Backend

Python version

Jupyter version

Installation

Activity

tacaswell commented on Sep 20, 2024

ianthomas23 commented on Sep 21, 2024

Simon-Stone commented on Sep 21, 2024

ianthomas23 commented on Sep 23, 2024

Simon-Stone commented on Sep 23, 2024

ianthomas23 commented on Sep 23, 2024

Simon-Stone commented on Sep 23, 2024

ianthomas23 commented on Sep 23, 2024

Simon-Stone commented on Sep 23, 2024

ianthomas23 commented on Sep 24, 2024

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QuLogic commented on Oct 10, 2024

ianthomas23 commented on Oct 10, 2024

ksunden commented on Jul 25, 2025

tacaswell commented on Jul 25, 2025

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