# Error after installing VMTK extension: "vtkvmtk module is not loaded"

**URL:** <https://discourse.slicer.org/t/error-after-installing-vmtk-extension-vtkvmtk-module-is-not-loaded/42008>\
**Category:** Support\
**Tags:** vmtk\
**Created:** [March 7, 2025, 7:50am UTC](https://discourse.slicer.org/t/error-after-installing-vmtk-extension-vtkvmtk-module-is-not-loaded/42008 "2025-03-07T07:50:46Z")\
**Posts on this page:** 10\
**Page:** 1

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**Author:** ![feiyu](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/feiyu/32/79464_2.png) [@feiyu](https://discourse.slicer.org/u/feiyu)\
**Post date:** [March 7, 2025, 7:50am UTC](https://discourse.slicer.org/t/error-after-installing-vmtk-extension-vtkvmtk-module-is-not-loaded/42008/1 "2025-03-07T07:50:46Z")

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I tried to use the VMTK extension for vessel segmentation, but I can’t find it in the Modules. However, I can see that the latest version of VMTK has been downloaded in the extension manager. Can anyone help me with this?

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**Author:** ![feiyu](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/feiyu/32/79464_2.png) [@feiyu](https://discourse.slicer.org/u/feiyu)\
**Post date:** [March 7, 2025, 7:55am UTC](https://discourse.slicer.org/t/error-after-installing-vmtk-extension-vtkvmtk-module-is-not-loaded/42008/2 "2025-03-07T07:55:30Z")

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![image](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/7/5/7529392667771b73c7ae5bb1fd3352015776969b.png)

 ![image](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/5/6/565a556c3ae36da535e50a8082364c53c6adb660.png)

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**Author:** ![cpinter](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/cpinter/32/7995_2.png) [@cpinter](https://discourse.slicer.org/u/cpinter)\
**Post date:** [March 7, 2025, 10:47am UTC](https://discourse.slicer.org/t/error-after-installing-vmtk-extension-vtkvmtk-module-is-not-loaded/42008/3 "2025-03-07T10:47:11Z")

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What Slicer version are you using? If older than 5.8 I suggest using 5.8, because we can only fix issues in the latest version. Thanks!

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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:** [March 7, 2025, 12:50pm UTC](https://discourse.slicer.org/t/error-after-installing-vmtk-extension-vtkvmtk-module-is-not-loaded/42008/4 "2025-03-07T12:50:12Z")

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Probably you have run into this issue:

> <https://github.com/vmtk/SlicerExtension-VMTK/issues/22#issuecomment-699000634>
>
> This error is reported at Slicer startup if SlicerVMTK extension is installed:
> …
> \`\`\`
> CLI executable: C:/Users/E/AppData/Roaming/NA-MIC/Extensions-29387/SlicerVMTK/lib/Slicer-4.11/qt-loadable-modules/vtkvmtk.py
> The process failed to start. Either the invoked program is missing, or you may have insufficient permissions to invoke the program.
> Fail to instantiate module “vtkvmtk”
> The following modules failed to be instantiated:
> vtkvmtk
> \`\`\`

This is a false alarm and the message can be safely ignored, because there is no such Slicer module as “vtkvmtk”. There is a file by that name in the module folder, but it is not a Slicer module, it should not be loaded, and it is not loaded. The only problem is the error message itself.

Let us know if you don’t find any of the actually existing [VMTK modules](https://github.com/vmtk/SlicerExtension-VMTK?tab=readme-ov-file#usage).

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**Author:** ![feiyu](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/feiyu/32/79464_2.png) [@feiyu](https://discourse.slicer.org/u/feiyu)\
**Post date:** [March 8, 2025, 8:02am UTC](https://discourse.slicer.org/t/error-after-installing-vmtk-extension-vtkvmtk-module-is-not-loaded/42008/5 "2025-03-08T08:02:27Z")

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The version I am using is 5.8.1, the latest stable version.

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**Author:** ![feiyu](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/feiyu/32/79464_2.png) [@feiyu](https://discourse.slicer.org/u/feiyu)\
**Post date:** [March 8, 2025, 8:14am UTC](https://discourse.slicer.org/t/error-after-installing-vmtk-extension-vtkvmtk-module-is-not-loaded/42008/6 "2025-03-08T08:14:58Z")

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This forum recommends the VMTK extension for vascular segmentation. If the VMTK extension is not available, what would I download in the extension manager interface, and how should I use it?

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**Author:** ![feiyu](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/feiyu/32/79464_2.png) [@feiyu](https://discourse.slicer.org/u/feiyu)\
**Post date:** [March 8, 2025, 8:19am UTC](https://discourse.slicer.org/t/error-after-installing-vmtk-extension-vtkvmtk-module-is-not-loaded/42008/7 "2025-03-08T08:19:46Z")

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![image](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/d/5/d5172ef4c8e55595fbd6f35ee62f0cf558a1b272.png)  
I download it in the extension manager interface

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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:** [March 8, 2025, 1:46pm UTC](https://discourse.slicer.org/t/error-after-installing-vmtk-extension-vtkvmtk-module-is-not-loaded/42008/8 "2025-03-08T13:46:50Z")

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The SlicerVMTK extension installs Slicer modules that have names you can review at:

> **[GitHub - vmtk/SlicerExtension-VMTK](https://github.com/vmtk/SlicerExtension-VMTK?tab=readme-ov-file#usage)**
>
> Contribute to vmtk/SlicerExtension-VMTK development by creating an account on GitHub.

It is currently a bug that a Slicer module named vtkvmtk is attempted to be loaded.

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<div class="post-metadata">

**Author:** ![feiyu](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/feiyu/32/79464_2.png) [@feiyu](https://discourse.slicer.org/u/feiyu)\
**Post date:** [March 9, 2025, 12:44am UTC](https://discourse.slicer.org/t/error-after-installing-vmtk-extension-vtkvmtk-module-is-not-loaded/42008/9 "2025-03-09T00:44:42Z")

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![image](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/5/f/5fc1d72660dc0ad34eaf81af271808531a0f4bd4.png)  
 ![image](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/f/0/f0700f8d52d6a4567eff4f1f4eebbee7a98093c5.jpeg)  
Comparing these two images, it is clear that simply clicking the “FULL TEXT” option revealed four loadable modules, while VMTK itself appears to be unloadable. Is this a bug in the developer’s design? I couldn’t find the latest VMTK extension tutorial on GitHub. Could you provide a link? Thank you!

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<div class="post-metadata">

**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:** [March 9, 2025, 3:54am UTC](https://discourse.slicer.org/t/error-after-installing-vmtk-extension-vtkvmtk-module-is-not-loaded/42008/10 "2025-03-09T03:54:20Z")

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The bug is that vtkvmtk shows up at all as a Slicer module. It should not be there as it is not a Slicer module.

The SlicerVMTK extension provides a collection of Slicer modules. Some of them contain a description that included the text “VMTK” such as “Clip Vessel” which is a module provided by SlicerVMTK.

The complete list of Slicer modules that come with SlicerVMTK can be viewed at:

> **[GitHub - vmtk/SlicerExtension-VMTK](https://github.com/vmtk/SlicerExtension-VMTK?tab=readme-ov-file#usage)**
>
> Contribute to vmtk/SlicerExtension-VMTK development by creating an account on GitHub.