# FALLBACK (log once): Fallback to SW vertex for line stipple

**URL:** <https://community.freefem.org/t/fallback-log-once-fallback-to-sw-vertex-for-line-stipple/4201>\
**Category:** General Discussion\
**Created:** [January 24, 2026, 9:43am UTC](https://community.freefem.org/t/fallback-log-once-fallback-to-sw-vertex-for-line-stipple/4201 "2026-01-24T09:43:01Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![zxss](https://avatars.discourse-cdn.com/v4/letter/z/bc8723/32.png) [@zxss](https://community.freefem.org/u/zxss)\
**Post date:** [January 24, 2026, 9:43am UTC](https://community.freefem.org/t/fallback-log-once-fallback-to-sw-vertex-for-line-stipple/4201/1 "2026-01-24T09:43:01Z")

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Dear all,

I am solving a 3D NS equation,

[3D flow around a cylinder\_312.edp](https://community.freefem.org/uploads/short-url/4Zt2DkSPPDXks3VPuqlWcc4ONPt.edp) (2.6 KB)

I solve it directly with UMFPACK and encounter the following tip

 ![Screenshot 2026-01-24 at 09.41.49](https://canada1.discourse-cdn.com/flex030/uploads/freefem/original/2X/e/ea0bed3ce724ed1a0e06a9d40013ee5620744b2e.jpeg)

has anyone met such situation. I don’t understand what does it mean?

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**Author:** ![prj](https://avatars.discourse-cdn.com/v4/letter/p/ecae2f/32.png) [@prj](https://community.freefem.org/u/prj)\
**Post date:** [January 25, 2026, 4:18am UTC](https://community.freefem.org/t/fallback-log-once-fallback-to-sw-vertex-for-line-stipple/4201/2 "2026-01-25T04:18:19Z")

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It’s just a warning.