# 3D slicer for MAC cannot install slicer extensions

**URL:** <https://discourse.slicer.org/t/3d-slicer-for-mac-cannot-install-slicer-extensions/2945>\
**Category:** Support\
**Created:** [May 27, 2018, 1:45pm UTC](https://discourse.slicer.org/t/3d-slicer-for-mac-cannot-install-slicer-extensions/2945 "2018-05-27T13:45:03Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![danceward](https://avatars.discourse-cdn.com/v4/letter/d/7c8e57/32.png) [@danceward](https://discourse.slicer.org/u/danceward)\
**Post date:** [May 27, 2018, 1:45pm UTC](https://discourse.slicer.org/t/3d-slicer-for-mac-cannot-install-slicer-extensions/2945/1 "2018-05-27T13:45:03Z")

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Operating system:Mac OS X  
Slicer version:4.8.1  
Expected behavior:install slicer extensions  
Actual behavior:Extensions can not be installed

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**Author:** ![lassoan](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/lassoan/32/13_2.png) [@lassoan](https://discourse.slicer.org/u/lassoan)\
**Post date:** [May 27, 2018, 1:48pm UTC](https://discourse.slicer.org/t/3d-slicer-for-mac-cannot-install-slicer-extensions/2945/2 "2018-05-27T13:48:52Z")

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The most common issue is that you are behind a hospital or corporate firewall and proxy settings are not configured at operating system level, but only in your web browser.

You can follow these instructions for downloading and installing extensions manually: [https://www.slicer.org/wiki/Documentation/Nightly/SlicerApplication/ExtensionsManager#How\_to\_manually\_download\_an\_extension\_package.3F](https://www.slicer.org/wiki/Documentation/Nightly/SlicerApplication/ExtensionsManager#How_to_manually_download_an_extension_package.3F)

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**Author:** ![danceward](https://avatars.discourse-cdn.com/v4/letter/d/7c8e57/32.png) [@danceward](https://discourse.slicer.org/u/danceward)\
**Post date:** [May 27, 2018, 2:24pm UTC](https://discourse.slicer.org/t/3d-slicer-for-mac-cannot-install-slicer-extensions/2945/3 "2018-05-27T14:24:55Z")

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The problem has been solved.  
Thank you  
danceward

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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:** [May 28, 2018, 6:22pm UTC](https://discourse.slicer.org/t/3d-slicer-for-mac-cannot-install-slicer-extensions/2945/4 "2018-05-28T18:22:38Z")

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Not sure if this is what fixed it for @danceward, but a common scenario on mac is opening Slicer from the read-only disk image and then not being able to install extensions (since they are saved in the app folder on mac).