# Nvfortran error: Illegal instruction (core dumped)

**URL:** <https://forums.developer.nvidia.com/t/nvfortran-error-illegal-instruction-core-dumped/370976>\
**Category:** nvc, nvc++ and nvfortran\
**Created:** [May 21, 2026, 8:54pm UTC](https://forums.developer.nvidia.com/t/nvfortran-error-illegal-instruction-core-dumped/370976 "2026-05-21T20:54:14Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![jdelia](https://developer.download.nvidia.com/images/forums/profile-default-devtalk-84.png) [@jdelia](https://forums.developer.nvidia.com/u/jdelia)\
**Post date:** [May 21, 2026, 8:54pm UTC](https://forums.developer.nvidia.com/t/nvfortran-error-illegal-instruction-core-dumped/370976/1 "2026-05-21T20:54:14Z")

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Dear all.

With:

nvfortran --version  
nvfortran 26.3-0 64-bit target on x86-64 Linux -tp sandybridge  
NVIDIA Compilers and Tools  
Copyright (c) 2026, NVIDIA CORPORATION & AFFILIATES. All rights reserved.

and the test case

```auto
  program test
    implicit none
    integer , parameter :: irp = 8
    real (irp), parameter :: tercio = 1.0_irp / 3.0_irp
    real (irp), dimension (3) :: saj
    real (irp) :: pro, daj
    !
    write (*,*)" irp = ", irp
    write (*,*)" tercio = ", tercio
    !
    saj = [0.4222131572793589_irp, 0.3780741577882090_irp, 0.3290526856292827_irp]
    write (*,*)" saj = ", saj
    !
    pro = product (saj)
    write (*,*)" pro = ", pro
    !
    daj = pro**tercio
    write (*,*)" daj = ", daj
  end program test

```

I get the error message:

$ test.exe  
irp = 8  
tercio = 0.3333333333333333  
saj = 0.4222131572793589 0.3780741577882090 0.3290526856292827  
pro = 5.2525983880679063E-002  
Illegal instruction (core dumped) test.exe

Please, any suggestions on how to fix this?  
Thanks in advance..

Regards,  
Jorge D’Elia.

---

<div class="post-metadata">

**Author:** ![MatColgrove](https://sea2.discourse-cdn.com/nvidia/user_avatar/forums.developer.nvidia.com/matcolgrove/32/14047_2.png) [@MatColgrove](https://forums.developer.nvidia.com/u/MatColgrove)\
**Post date:** [May 21, 2026, 9:09pm UTC](https://forums.developer.nvidia.com/t/nvfortran-error-illegal-instruction-core-dumped/370976/2 "2026-05-21T21:09:23Z")

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Hi Jorge,

This is a [known issue](https://forums.developer.nvidia.com/t/nvfortran-ignores-options-to-compile-without-avx2-instructions-sandybridge-processor/366224) when using the dexp intrinsic on Sandybridge. The intrinsic being used has an AVX2 instruction which isn’t supported on Sandybridge.

I have an open report, TPR#38436, and will add your post to it so I can notify you once a fix is included in a future release.

The work around is to compile with the “-tp px” flag, to target a generic x86 system.

-Mat

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<div class="post-metadata">

**Author:** ![jdelia](https://developer.download.nvidia.com/images/forums/profile-default-devtalk-84.png) [@jdelia](https://forums.developer.nvidia.com/u/jdelia)\
**Post date:** [May 22, 2026, 11:57am UTC](https://forums.developer.nvidia.com/t/nvfortran-error-illegal-instruction-core-dumped/370976/3 "2026-05-22T11:57:25Z")

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> [@MatColgrove](#):
>
> [known issue](https://forums.developer.nvidia.com/t/nvfortran-ignores-options-to-compile-without-avx2-instructions-sandybridge-processor/366224) when using the dexp intrinsic on Sandybridge.

Hi Mat,

Thanks for your reply with the observations and suggestions. It worked ok! Also, thanks with to be included in the open report TPR#38436.

Regards.  
Jorge.

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<div class="post-metadata">

**Author:** ![system](https://sea2.discourse-cdn.com/nvidia/user_avatar/forums.developer.nvidia.com/system/32/68080_2.png) [@system](https://forums.developer.nvidia.com/u/system)\
**Post date:** [June 5, 2026, 11:57am UTC](https://forums.developer.nvidia.com/t/nvfortran-error-illegal-instruction-core-dumped/370976/4 "2026-06-05T11:57:48Z")

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