AttributeError: 'FakeIPython' object has no attribute 'register_magic_function'

[joshuasundance-swca]

Expected Behavior

Solara runs as server app as reliably as it does in a notebook when imported code uses IPython.core.magic.register_cell_magic

Current Behavior

Code that calls from IPython.core.magic.register_cell_magic in a context that uses an instance of solara.server.patch.FakeIPython will result in the AttributeError in the title of this issue:

AttributeError: 'FakeIPython' object has no attribute 'register_magic_function'

Steps to Reproduce the Problem

1. Write solara code that imports code that uses register_cell_magic, for example mermaid-py: from mermaid import Mermaid as seen below
2. Observe that it works in a Jupyter notebook
3. Observe that using solara run results in AttributeError

App with the following code fails with solara run but works in notebook:

import solara
from mermaid import Mermaid

Workaround

import solara.server.patch


# Patch the FakeIPython class to add register_magic_function
def noop_register_magic_function(self, *args, **kwargs):
    pass


# I looked at mermaid-py's use of register_magic_function and I don't need it
solara.server.patch.FakeIPython.register_magic_function = noop_register_magic_function

import solara
from mermaid import Mermaid

Specifications

• Solara Version: 1.51.1

• Platform: Docker on Windows python:3.13.7-slim-trixie

  • uname -a: Linux f6f919b954ee 6.6.87.2-microsoft-standard-WSL2 #1 SMP PREEMPT_DYNAMIC Thu Jun 5 18:30:46 UTC 2025 x86_64 GNU/Linux

• Affected Python Versions: 3.13.7