# 3D slicer 4.10 can't load structures

**URL:** <https://discourse.slicer.org/t/3d-slicer-4-10-cant-load-structures/4593>\
**Category:** Support\
**Created:** [October 30, 2018, 4:02pm UTC](https://discourse.slicer.org/t/3d-slicer-4-10-cant-load-structures/4593 "2018-10-30T16:02:52Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![aseman](https://avatars.discourse-cdn.com/v4/letter/a/c0e974/32.png) [@aseman](https://discourse.slicer.org/u/aseman)\
**Post date:** [October 30, 2018, 4:02pm UTC](https://discourse.slicer.org/t/3d-slicer-4-10-cant-load-structures/4593/1 "2018-10-30T16:02:52Z")

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Operating system:windows 10  
Slicer version:4.10  
Hi 3D slicer experts and all  
I installed 3D Slicer 4.10 ; but unfortunately , when I load structures the following error message is shown.(figure 1) ; and the CT images are not displayed(figure2). also, I can’t install any Extension from Extension Manager. Can you help me about these problems.  
Thanks a lot  
 ![](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/3/c/3c4bfe03c1bcf62efdefef8a6a4fb3019dfb45e6.png)

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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:** [October 30, 2018, 4:03pm UTC](https://discourse.slicer.org/t/3d-slicer-4-10-cant-load-structures/4593/2 "2018-10-30T16:03:44Z")

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You need to install SlicerRT extension to be able to load RT structure sets.

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<div class="post-metadata">

**Author:** ![aseman](https://avatars.discourse-cdn.com/v4/letter/a/c0e974/32.png) [@aseman](https://discourse.slicer.org/u/aseman)\
**Post date:** [October 30, 2018, 4:06pm UTC](https://discourse.slicer.org/t/3d-slicer-4-10-cant-load-structures/4593/3 "2018-10-30T16:06:15Z")

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thank you for your guideline. but I can’t install any Extension. can you help me?

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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:** [October 30, 2018, 5:02pm UTC](https://discourse.slicer.org/t/3d-slicer-4-10-cant-load-structures/4593/4 "2018-10-30T17:02:31Z")

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See installation instructions [here](https://www.slicer.org/wiki/Documentation/Nightly/SlicerApplication/ExtensionsManager#Installing_an_extension). Name of the extension that you need to install is _SlicerRT_.

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<div class="post-metadata">

**Author:** ![aseman](https://avatars.discourse-cdn.com/v4/letter/a/c0e974/32.png) [@aseman](https://discourse.slicer.org/u/aseman)\
**Post date:** [October 30, 2018, 8:37pm UTC](https://discourse.slicer.org/t/3d-slicer-4-10-cant-load-structures/4593/5 "2018-10-30T20:37:51Z")

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Hi  
I’m sorry for my questions! but my problem with installing Extensions is that the page associated with Extension Manager is like the following figure ; and no Extensions are visible for selection . I installed and uninstalled the slicer several times, but it was not effective. please guide me.  
thank you

 ![extension](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/a/1/a133a1b9cdb660802d6cd4146f6c8232640ac536.png)

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<div class="post-metadata">

**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:** [October 30, 2018, 9:08pm UTC](https://discourse.slicer.org/t/3d-slicer-4-10-cant-load-structures/4593/6 "2018-10-30T21:08:49Z")

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Is it an official Slicer-4.10 build? Is it possible that your computer is behind a firewall?

Anyway, you can follow [these instructions](https://www.slicer.org/wiki/Documentation/Nightly/SlicerApplication/ExtensionsManager#Installing_an_extension_without_network_connection) for downloading an extension using a web browser and installing it manually.