# Mac extension builds failing with cout error

**URL:** <https://discourse.slicer.org/t/mac-extension-builds-failing-with-cout-error/46685>\
**Category:** Development\
**Tags:** extensions\
**Created:** [April 8, 2026, 2:18pm UTC](https://discourse.slicer.org/t/mac-extension-builds-failing-with-cout-error/46685 "2026-04-08T14:18:20Z")\
**Posts on this page:** 1\
**Showing post:** 14

<div class="post-metadata">

**Author:** ![Sam\_Horvath](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/sam_horvath/32/3092_2.png) [@Sam\_Horvath](https://discourse.slicer.org/u/Sam_Horvath)\
**Post date:** [April 10, 2026, 3:04pm UTC](https://discourse.slicer.org/t/mac-extension-builds-failing-with-cout-error/46685/14 "2026-04-10T15:04:29Z")

</div>

Fix log (unchecked are in progress):

SlicerDMRI  
 SlicerRT : [Iostream missing include fixes by sjh26 · Pull Request #314 · SlicerRt/SlicerRT · GitHub](https://github.com/SlicerRt/SlicerRT/pull/314)  
 MeshToLabelMap  
 SlicerVMTK: Pending this vmtk fix, [Include iostream to build against VTK 9.6 by chir-set · Pull Request #481 · vmtk/vmtk · GitHub](https://github.com/vmtk/vmtk/pull/481), my branch here: [GitHub - sjh26/SlicerExtension-VMTK at fix-iostream · GitHub](https://github.com/sjh26/SlicerExtension-VMTK/tree/fix-iostream)  
 VASSTAlgorithms: [BUG: Add missing #include \<iostream\> to C++ files using cerr/endl by sjh26 · Pull Request #5 · VASST/VASSTAlgorithms · GitHub](https://github.com/VASST/VASSTAlgorithms/pull/5)  
 SlicerAutoscoperM: Autoscoper PR: [COMP: Fix build with VTK 9.6 by sjh26 · Pull Request #328 · BrownBiomechanics/Autoscoper · GitHub](https://github.com/BrownBiomechanics/Autoscoper/pull/328)  
 CarreraSlice: [COMP: Fix iostream include hygiene across C++ sources (VTK 9.6 compat) by sjh26 · Pull Request #14 · ikolesov/CarreraSlice · GitHub](https://github.com/ikolesov/CarreraSlice/pull/14)  
 CMFreg: [COMP: VTK 9.6 build fix - iostream include hygiene by sjh26 · Pull Request #41 · DCBIA-OrthoLab/CMFreg · GitHub](https://github.com/DCBIA-OrthoLab/CMFreg/pull/41)  
 PortPlacement: [COMP: VTK 9.6 build fix - add missing \<iostream\> include by sjh26 · Pull Request #4 · SlicerIGT/PortPlacement · GitHub](https://github.com/SlicerIGT/PortPlacement/pull/4)  
 ShapeVariationAnalyzer: [COMP: VTK 9.6 Build Fix - Fix iostream include hygiene by sjh26 · Pull Request #72 · DCBIA-OrthoLab/ShapeVariationAnalyzer · GitHub](https://github.com/DCBIA-OrthoLab/ShapeVariationAnalyzer/pull/72)  
 SlicerFreeSurfer: [COMP: VTK 9.6 Build Fix - Fix iostream include hygiene by sjh26 · Pull Request #22 · PerkLab/SlicerFreeSurfer · GitHub](https://github.com/PerkLab/SlicerFreeSurfer/pull/22)

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