# Slicer 5.12.3 plans and fixing the macOS stable extension packages

**URL:** <https://discourse.slicer.org/t/slicer-5-12-3-plans-and-fixing-the-macos-stable-extension-packages/47715>\
**Category:** Development\
**Created:** [July 22, 2026, 4:59pm UTC](https://discourse.slicer.org/t/slicer-5-12-3-plans-and-fixing-the-macos-stable-extension-packages/47715 "2026-07-22T16:59:05Z")\
**Posts on this page:** 10\
**Page:** 1

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**Author:** ![ebrahim](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/ebrahim/32/13403_2.png) [@ebrahim](https://discourse.slicer.org/u/ebrahim)\
**Post date:** [July 22, 2026, 4:59pm UTC](https://discourse.slicer.org/t/slicer-5-12-3-plans-and-fixing-the-macos-stable-extension-packages/47715/1 "2026-07-22T16:59:06Z")

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Yesterday we merged [Slicer#9302](https://github.com/Slicer/Slicer/pull/9302) which worked out the cause of the issue with macOS C++ extension packages on Slicer 5.12, and which hopefully resolved the issue.

Today there’s good evidence from the nightly packages that the issue is resolved:

- Yesterday’s MarkupsToModel: [SPKC](https://slicer-packages.kitware.com/#item/6a5fa0982eb3d967f03121e1) (see the large file size, indicating duplicated libraries)
- Today’s: [SPKC](https://slicer-packages.kitware.com/#item/6a60ddab2eb3d967f0320816) (much smaller!)

Time to cut Slicer 5.12.3? @lassoan @pieper @Sam_Horvath @jamesobutler ? Any other commits we should include besides [2c4c53a](https://github.com/Slicer/Slicer/commit/2c4c53aaa487c1bfde9237b12a92f6a8b60b61b9)?

I am thinking this time I will keep the `pre_release` attribute as True until we test that the problem is really resolved on macOS, preventing anything from becoming available on the download page until we are ready.

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**Author:** ![pieper](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/pieper/32/8_2.png) [@pieper](https://discourse.slicer.org/u/pieper)\
**Post date:** [July 22, 2026, 5:36pm UTC](https://discourse.slicer.org/t/slicer-5-12-3-plans-and-fixing-the-macos-stable-extension-packages/47715/2 "2026-07-22T17:36:08Z")

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Confirmed - MarkupsToModel and SlicerRT work for me on today’s mac build. Yes for 5.12.3 👍

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**Author:** ![ebrahim](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/ebrahim/32/13403_2.png) [@ebrahim](https://discourse.slicer.org/u/ebrahim)\
**Post date:** [July 23, 2026, 2:12pm UTC](https://discourse.slicer.org/t/slicer-5-12-3-plans-and-fixing-the-macos-stable-extension-packages/47715/3 "2026-07-23T14:12:44Z")

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Here is a signed and notarized macOS 5.12.3 package:

[https://slicer-packages.kitware.com/api/v1/file/hashsum/SHA512/2076f23458936a028d3d1a91686369b5979d3373012f11db0e90c30fdb34874eec2b150da4d5225b2ac6b1bf5552795e1783e621a8ae3c39c01983593b07283a/download](https://slicer-packages.kitware.com/api/v1/file/hashsum/SHA512/2076f23458936a028d3d1a91686369b5979d3373012f11db0e90c30fdb34874eec2b150da4d5225b2ac6b1bf5552795e1783e621a8ae3c39c01983593b07283a/download)

It is still marked as pre-release so it is not going to be available on the download page yet.  
Once we confirm the issue is really solved, I will remove the pre-release tag.

Can someone try this out on macOS and confirm that C++ extensions work?

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**Author:** ![jamesobutler](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/jamesobutler/32/7511_2.png) [@jamesobutler](https://discourse.slicer.org/u/jamesobutler)\
**Post date:** [July 23, 2026, 2:23pm UTC](https://discourse.slicer.org/t/slicer-5-12-3-plans-and-fixing-the-macos-stable-extension-packages/47715/4 "2026-07-23T14:23:42Z")

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I’ve installed 5.12.3 along with SegmentEditorExtraEffects which pulls in MarkupsToModel that was previously impacted. I can confirm that on restart the MarkupsToModel now loads successfully and I can use the “Surface cut” segment editor effect successfully which utilizes the MarkupsToModel logic.

 ![image](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/b/3/b392b8abcc60710355f761be8d7ca548ac20252d.jpeg)

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**Author:** ![ebrahim](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/ebrahim/32/13403_2.png) [@ebrahim](https://discourse.slicer.org/u/ebrahim)\
**Post date:** [July 23, 2026, 2:27pm UTC](https://discourse.slicer.org/t/slicer-5-12-3-plans-and-fixing-the-macos-stable-extension-packages/47715/5 "2026-07-23T14:27:49Z")

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Yay! Taking the patch release to the finish line

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**Author:** ![muratmaga](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/muratmaga/32/3622_2.png) [@muratmaga](https://discourse.slicer.org/u/muratmaga)\
**Post date:** [July 23, 2026, 3:06pm UTC](https://discourse.slicer.org/t/slicer-5-12-3-plans-and-fixing-the-macos-stable-extension-packages/47715/6 "2026-07-23T15:06:37Z")

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Yes, working for me too. Thank you.

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**Author:** ![GeneRisi](https://avatars.discourse-cdn.com/v4/letter/g/ba8739/32.png) [@GeneRisi](https://discourse.slicer.org/u/GeneRisi)\
**Post date:** [July 24, 2026, 2:37am UTC](https://discourse.slicer.org/t/slicer-5-12-3-plans-and-fixing-the-macos-stable-extension-packages/47715/7 "2026-07-24T02:37:23Z")

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I downloaded it and was surprised to see that it is still an Intel processor app. Is the native version not ready yet?

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**Author:** ![muratmaga](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/muratmaga/32/3622_2.png) [@muratmaga](https://discourse.slicer.org/u/muratmaga)\
**Post date:** [July 24, 2026, 2:43am UTC](https://discourse.slicer.org/t/slicer-5-12-3-plans-and-fixing-the-macos-stable-extension-packages/47715/8 "2026-07-24T02:43:50Z")

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That is planned for Slicer 6.0.

This release is meant to provide a bridge while the developers do many substantial changes to the core in preparation for Slicer 6.0, and break things for a while (in the preview versions). Given there is there is still rosetta support for at least a year, I think this is fine.

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**Author:** ![pieper](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/pieper/32/8_2.png) [@pieper](https://discourse.slicer.org/u/pieper)\
**Post date:** [July 24, 2026, 1:50pm UTC](https://discourse.slicer.org/t/slicer-5-12-3-plans-and-fixing-the-macos-stable-extension-packages/47715/9 "2026-07-24T13:50:08Z")

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Yes, @muratmaga is right, we plan to make arm64 mac builds available once a few more bugs are sorted out. No show stoppers, just a matter of getting the machine in place and updating the download page. We’ll probably post some native arm64 installers somewhere for testing before long.

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**Author:** ![GeneRisi](https://avatars.discourse-cdn.com/v4/letter/g/ba8739/32.png) [@GeneRisi](https://discourse.slicer.org/u/GeneRisi)\
**Post date:** [July 25, 2026, 1:32am UTC](https://discourse.slicer.org/t/slicer-5-12-3-plans-and-fixing-the-macos-stable-extension-packages/47715/10 "2026-07-25T01:32:49Z")

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Excellent! Thank you!