Issue with the mesmerize-core 0.5.0's napari integration

[Maissa12-dot]

I am writing to report an issue I'm encountering while trying to use mesmerize-core with napari on my macOS system. It appears the mesmerize-core plugin is not being discovered by napari.

My System Information:

Operating System: macOS (Apple Silicon - M1)

Architecture: osx-arm64

Environment Setup:
I created a dedicated Conda environment using Mamba (from conda-forge and defaults channels) and installed mesmerize-core and its dependencies. I also attempted a separate installation using pip in a new environment, with the same result.

Installed Versions:

python: 3.10

mesmerize-core: 0.5.0

napari: 0.6.2

pyqt (for graphical backend): Installed and confirmed working.

Problem Description:
The napari viewer itself launches successfully without any issues. However, when I navigate to the Plugins menu within napari and then to Install/Uninstall Plugins (or "Plugin Manager"), mesmerize-core (or any variant of "mesmerize") does not appear in the list of installed or discoverable plugins.

Troubleshooting Steps Performed & Key Findings:

Attempted Direct Launch: Running python -m mesmerize_core.napari resulted in ModuleNotFoundError: No module named 'mesmerize_core.napari'.

Inspected mesmerize_core package content (Conda install): I navigated to /Users/maissa/miniconda3/envs/mesmerize_new_env/lib/python3.10/site-packages/mesmerize_core/ and performed ls -a.

Finding: The critical napari.yaml file was missing from this directory. There was also no napari.py file or napari subdirectory.

Attempted pip Installation (in a clean, new environment): I created a fresh Conda environment and installed napari (with napari[all]) and mesmerize-core using pip.

Finding: The behavior was identical; napari launched, but mesmerize-core did not appear in the plugin manager.

This suggests that the mesmerize-core 0.5.0 package for osx-arm64 (both via conda-forge and pip distribution) may be missing the necessary napari.yaml file or is not correctly configured for napari plugin discovery in its current form.

Could you please advise on the correct method to install and launch the mesmerize-core GUI within napari on an Apple Silicon Mac, or if this is a known issue with the current package version?

Thank you for your time and assistance.

Sincerely,

[kushalkolar]

Hi, thanks for posting.

There is no mesmerize napari plugin, we tried to make one a few years ago but long story short napari is based on older graphics technologies and is not fast enough for large scale calcium imaging visualization. We recommend using mesmerize-viz which uses fastplotlib based on newer graphics technologies for visualization.

[Maissa12-dot]

Thank you so much for your answer.
I tried to install the mesmerize vis and the fastplotlib but I'm experiencing a critical ModuleNotFoundError: No module named 'fastplotlib' when using mesmerize-viz 0.1.0 on macOS (Python 3.10).

Extensive troubleshooting shows that pip install mesmerize-viz forces a downgrade of fastplotlib to 0.1.0a16 (and pygfx to 0.1.17), even when newer, working versions (like fastplotlib 0.5.0 from conda-forge) are available. This older fastplotlib version then fails to import.

This dependency pinning prevents mesmerize-viz from functioning. Could you please advise on a workaround or if an updated mesmerize-viz version with newer fastplotlib dependencies is planned?

[Maissa12-dot]

Hello, thank you for your answer, I tried the mesmerize which uses the fastpotlib, but I'm facing some problems, It appears the issue is not with my installation process, but rather with the mesmerize-viz 0.1.0 package's specific dependency on fastplotlib==0.1.0a16. This particular alpha version of fastplotlib seems to be either corrupted, buggy, or fundamentally incompatible with my macOS Apple Silicon setup, leading to the AttributeError. Newer versions of fastplotlib (e.g., 0.2.0 to 0.5.0) exist and likely have a stable Figure API, but mesmerize-viz 0.1.0 is pinned to the problematic 0.1.0a16. Could you please provide guidance on this issue? - Is there a known workaround for the AttributeError: module 'fastplotlib' has no attribute 'Figure' with fastplotlib==0.1.0a16 on macOS M1? - Are there plans for a newer mesmerize-viz release that updates its fastplotlib dependency to a more stable version? - Is there a specific fastplotlib version you recommend that is compatible with mesmerize-viz 0.1.0 and works on Apple Silicon? Thank you for your time and assistance. Le ven. 4 juil. 2025 à 10:02, Kushal Kolar ***@***.***> a écrit :

…

Hi, thanks for posting. There is no mesmerize napari plugin, we tried to make one a few years ago but long story short napari is based on older graphics technologies and is not fast enough for large scale calcium imaging visualization. We recommend using mesmerize-viz <https://github.com/kushalkolar/mesmerize-viz> which uses fastplotlib <https://github.com/fastplotlib/fastplotlib> based on newer graphics technologies for visualization. — Reply to this email directly, view it on GitHub <#333 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/BUIYR7FVQ2XGIK2PTSOBRG33GYYI3AVCNFSM6AAAAACAYXIAVCVHI2DSMVQWIX3LMV43URDJONRXK43TNFXW4Q3PNVWWK3TUHMYTGNRWGA2DSNA> . You are receiving this because you authored the thread.Message ID: ***@***.***>

-- Ben Mahmoud Maissa

[kushalkolar]

mesmerize-viz is pinned to an older fastplotlib because it works with that API, if you're just using mesmerize-viz it should work, what exactly are you trying to do? Can you provide what code you're running.