# Dealing with fallback errors

**URL:** <https://community.freefem.org/t/dealing-with-fallback-errors/2234>\
**Category:** General Discussion\
**Created:** [January 21, 2023, 12:35am UTC](https://community.freefem.org/t/dealing-with-fallback-errors/2234 "2023-01-21T00:35:35Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![jsmacd](https://avatars.discourse-cdn.com/v4/letter/j/df788c/32.png) [@jsmacd](https://community.freefem.org/u/jsmacd)\
**Post date:** [January 21, 2023, 12:35am UTC](https://community.freefem.org/t/dealing-with-fallback-errors/2234/1 "2023-01-21T00:35:35Z")

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I’m funning FreeFEM on a macbook. My program runs on coarse grids, but when I try to refine I am getting the following error:

FALLBACK (log once): Fallback to SW vertex processing (lineMode && (localGroupInfo & GLRGroupInfoPrimitiveEmulatedFill))  
FALLBACK (log once): Fallback to SW vertex processing, m\_disable\_code: 800  
FALLBACK (log once): Fallback to SW vertex processing in drawCore, m\_disable\_code: 800

I’ve learnt that this error is coming from the Apple M1 OpenGl driver when you use a double in a fragment shader. I’m not sure what that means, but is there a way to force the program to run without doing that?

Note that I can run the exact same program for a similar equation, but with a different solution, on all the refined grids that I’d like.

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**Author:** ![frederichecht](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.freefem.org/frederichecht/32/15_2.png) [@frederichecht](https://community.freefem.org/u/frederichecht)\
**Post date:** [September 28, 2023, 10:52am UTC](https://community.freefem.org/t/dealing-with-fallback-errors/2234/2 "2023-09-28T10:52:39Z")

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I think, it is not difficult to change the type of vertex in ffglut.cpp to make the conservation in c++ not i OpenGL.

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**Author:** ![jsmacd](https://avatars.discourse-cdn.com/v4/letter/j/df788c/32.png) [@jsmacd](https://community.freefem.org/u/jsmacd)\
**Post date:** [September 28, 2023, 2:58pm UTC](https://community.freefem.org/t/dealing-with-fallback-errors/2234/3 "2023-09-28T14:58:59Z")

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Thank you Professor for the response! This problem I believe I fixed by changing the solver type. I will look into your suggestion as well 🙂