# vtkSTLReader fails, when binary STL starts with keyword 'solid'

**URL:** https://discourse.vtk.org/t/vtkstlreader-fails-when-binary-stl-starts-with-keyword-solid/16539
**Category:** Support
**Created:** [September 17, 2026, 7:55am UTC](https://discourse.vtk.org/t/vtkstlreader-fails-when-binary-stl-starts-with-keyword-solid/16539 "2026-09-17T07:55:40Z")
**Posts on this page:** 4
**Page:** 1

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### Author: ![HST](https://discourse.vtk.org/letter_avatar_proxy/v4/letter/h/b38774/32.png) [@HST](https://discourse.vtk.org/u/HST)
#### Post date: [September 17, 2026, 7:55am UTC](https://discourse.vtk.org/t/vtkstlreader-fails-when-binary-stl-starts-with-keyword-solid/16539/1 "2026-09-17T07:55:40Z")

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In VTK 9.7.0 the vtkSTLReader fails, when a binary STL file starts with the keyword ‘solid’. I used version 9.5.2 before. This version accepted the same file.

In the described case, vtkSTLReader::ReadASCIISTL() is called to read the binary STL and fails. Using vtkSTLReader::RelaxedConformanceOn() does not solve this issue.

I need to replace the ‘solid’ keyword in binary STL files, to be able to use vtkSTLReader.

I think the behavior is too strict, even if the usage of the ‘solid’ keyword in binary STL files does not comply with the STL guidelines.

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### Author: ![mwestphal](https://discourse.vtk.org/user_avatar/discourse.vtk.org/mwestphal/32/19_2.png) [@mwestphal](https://discourse.vtk.org/u/mwestphal)
#### Post date: [September 17, 2026, 8:32am UTC](https://discourse.vtk.org/t/vtkstlreader-fails-when-binary-stl-starts-with-keyword-solid/16539/2 "2026-09-17T08:32:39Z")

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Use “RelaxedConformance” mode.

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### Author: ![HST](https://discourse.vtk.org/letter_avatar_proxy/v4/letter/h/b38774/32.png) [@HST](https://discourse.vtk.org/u/HST)
#### Post date: [September 18, 2026, 5:40am UTC](https://discourse.vtk.org/t/vtkstlreader-fails-when-binary-stl-starts-with-keyword-solid/16539/3 "2026-09-18T05:40:46Z")

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Thanks, that actually seems to work. I thought I had tried that without success.

Sorry for the unnecessary post.

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### Author: ![mwestphal](https://discourse.vtk.org/user_avatar/discourse.vtk.org/mwestphal/32/19_2.png) [@mwestphal](https://discourse.vtk.org/u/mwestphal)
#### Post date: [September 18, 2026, 6:14am UTC](https://discourse.vtk.org/t/vtkstlreader-fails-when-binary-stl-starts-with-keyword-solid/16539/4 "2026-09-18T06:14:46Z")

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No worries, this post is good for visibility of this feature.