# Installation of extensions from files not working

**URL:** <https://discourse.slicer.org/t/installation-of-extensions-from-files-not-working/31403>\
**Category:** Support\
**Tags:** extensions-manager, extensions\
**Created:** [August 28, 2023, 12:56pm UTC](https://discourse.slicer.org/t/installation-of-extensions-from-files-not-working/31403 "2023-08-28T12:56:55Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![ga1g](https://avatars.discourse-cdn.com/v4/letter/g/cc9497/32.png) [@ga1g](https://discourse.slicer.org/u/ga1g)\
**Post date:** [August 28, 2023, 12:56pm UTC](https://discourse.slicer.org/t/installation-of-extensions-from-files-not-working/31403/1 "2023-08-28T12:56:55Z")

</div>

Hi,  
I have a stand-alone computer with no internet connection, which I want to add extensions to. The downloaded extension files are installed but the functionality in Slicer is missing.  
Also when I click “more…” in the extension manager i get the following error:  
“Extensions can not be installed.  
Failed to load extension page using this URL: [@KitwareMedical/slicer-extensions-webapp](https://extensions.slicer.org/catalog/All/31938/win)  
Check that 3D Slicer is properly installed. Read more…”

This happens with several extensions such as “SegmentEditorExtraEffects” “AirwaySegmentation” and " “MarkupsToModel”

A test on another computer had the same results, but when established an internet connection an extra download was done. Still extensions do not work.  
Thank you  
Gal.