Hi Nikita, using conda and pip together in one environment can sometimes lead to issues. I had this problem a lot, and not only with larch. What worked very well for me was using the pixi package manager ( https://urldefense.us/v3/__https://pixi.prefix.dev/latest/__;!!G_uCfscf7eWS!... ). You can create one project environment for larch, set larix callable globally and never think about it again. Since then, all larch updates and installs work reliably across my win/lin and m3 devices, so it may also work for you. Best, Sebastian On Wed, 25 Feb 2026 at 15:00, wrote:

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Today's Topics:

1. Re: error message when installing Larch on macbookpro M1 (Matthew Newville)

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Message: 1 Date: Tue, 24 Feb 2026 16:11:21 +0000 From: Matthew Newville Subject: [Ifeffit] Re: error message when installing Larch on macbookpro M1 To: "ifeffit@millenia.cars.aps.anl.gov" Cc: Nikita Vostrov Message-ID: Content-Type: multipart/alternative; boundary="_000_MN6PR11MB821907 E82A5C52338AA4C4E39674AMN6PR11MB8219namp_"

Hi Nikita,

Sorry for the trouble. I have not been able to reproduce this myself, and I've seen others successfully install on a Macbook M1 (I am pretty sure the details of the architecture do not matter) with the PKG installer and GetLarch.sh script. I have also seen a few other broken installations, too. The packages that come from the Materials Project (including spglib) seem to be the most fragile.

If you reach the point where 'spglib' fails to build, it is almost certain you have a working conda Python environment that can be fixed in a Terminal (under Applications->Utilities). I would suggest opening a Terminal window and run ~/xraylarch/bin/conda install -c conda-forge spglib pymatgen

That may take some time, and it may install many more packages. But it should work. Then you can run ~/xraylarch/bin/python -m pip install "xraylarch[larix]" ~/xraylarch/bin/larch -m

Again, each of those may take some time. And, at the time, the 'larch -m" command will print out a lot of useless messages (only on MacOS, and on the list of things to fix).

--Matt

________________________________ From: Nikita Vostrov via Ifeffit Sent: Monday, February 23, 2026 11:23 AM To: ifeffit@millenia.cars.aps.anl.gov Cc: Nikita Vostrov Subject: [Ifeffit] Re: error message when installing Larch on macbookpro M1

Hello, I still get the same error posted in this thread even with the Python 3. 13. 10 installation script (also on m1 macbook). Sincerely, Nikita. ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ‍ ZjQcmQRYFpfptBannerStart This Message Is From an External Sender This message came from outside your organization.

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Hello,

I still get the same error posted in this thread even with the Python 3.13.10 installation script (also on m1 macbook).

Sincerely,

Nikita.