# Extension build error windows (MSCV version not recognized)

**URL:** <https://discourse.slicer.org/t/extension-build-error-windows-mscv-version-not-recognized/13770>\
**Category:** Support\
**Tags:** extensions-manager, radiomics\
**Created:** [September 30, 2020, 9:50am UTC](https://discourse.slicer.org/t/extension-build-error-windows-mscv-version-not-recognized/13770 "2020-09-30T09:50:15Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![JoostJM](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/joostjm/32/1091_2.png) [@JoostJM](https://discourse.slicer.org/u/JoostJM)\
**Post date:** [September 30, 2020, 9:50am UTC](https://discourse.slicer.org/t/extension-build-error-windows-mscv-version-not-recognized/13770/1 "2020-09-30T09:50:15Z")

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The SlicerRadiomics build on windows fails on the configuration step.  
From [the log](http://slicer.cdash.org/buildSummary.php?buildid=2025335) it appears that it detects a MSVC\_version of 1924, but just after that it states that this version is not found.

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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:** [September 30, 2020, 1:14pm UTC](https://discourse.slicer.org/t/extension-build-error-windows-mscv-version-not-recognized/13770/2 "2020-09-30T13:14:15Z")

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That’s because FindVcvars.cmake for the v4.10.2 tag only knows up to Visual Studio 2017 (see [here](https://github.com/Slicer/Slicer/blob/v4.10.2/CMake/FindVcvars.cmake#L132)), but the build machine now is using a newer Visual Studio 2019 version hence why it doesn’t know where to find the vcvars for this newer version. The latest Slicer code has an up-to-date version of FindVcvars.cmake (see [here](https://github.com/Slicer/Slicer/blob/5e203109175dbfebb1e5151daed0178f12125ef1/CMake/FindVcvars.cmake#L134)).

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<div class="post-metadata">

**Author:** ![JoostJM](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/joostjm/32/1091_2.png) [@JoostJM](https://discourse.slicer.org/u/JoostJM)\
**Post date:** [September 30, 2020, 4:52pm UTC](https://discourse.slicer.org/t/extension-build-error-windows-mscv-version-not-recognized/13770/3 "2020-09-30T16:52:27Z")

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Thanks for the links! However, I’m still a bit confused, why doesn’t my build system use the latest slicer code? Do I need to set something specific somewhere?

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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:** [September 30, 2020, 6:18pm UTC](https://discourse.slicer.org/t/extension-build-error-windows-mscv-version-not-recognized/13770/4 "2020-09-30T18:18:05Z")

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The log that you linked was the nightly build of SlicerRadiomics for the Slicer Stable 4.10.2. That is different from the nightly build of SlicerRadiomics for the Slicer Preview.

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<div class="post-metadata">

**Author:** ![JoostJM](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/joostjm/32/1091_2.png) [@JoostJM](https://discourse.slicer.org/u/JoostJM)\
**Post date:** [October 1, 2020, 9:15am UTC](https://discourse.slicer.org/t/extension-build-error-windows-mscv-version-not-recognized/13770/5 "2020-10-01T09:15:24Z")

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Ah thanks. I’ve confirmed the build is succeeding for the Nigthly build.