# Gmx covar range checking error

**URL:** <https://gromacs.bioexcel.eu/t/gmx-covar-range-checking-error/2245>\
**Category:** User discussions\
**Created:** [May 29, 2021, 12:08pm UTC](https://gromacs.bioexcel.eu/t/gmx-covar-range-checking-error/2245 "2021-05-29T12:08:43Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![veerubiotech](https://avatars.discourse-cdn.com/v4/letter/v/e480ec/32.png) [@veerubiotech](https://gromacs.bioexcel.eu/u/veerubiotech)\
**Post date:** [May 29, 2021, 12:08pm UTC](https://gromacs.bioexcel.eu/t/gmx-covar-range-checking-error/2245/1 "2021-05-29T12:08:43Z")

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GROMACS version: 2021  
GROMACS modification: Yes/No  
Dear All,  
I am using gromacs on windows 10 WSL2 ubuntu.  
While running - gmx covar -s step4.0\_minimization.tpr -f outputbox.xtc -n proteinAB\_SAM\_G3A\_Nacl.ndx, i got following error

Range checking error (possible bug):  
The provided structure file only contains 42820 coordinates, but coordinate  
index 3993 was requested for fitting. Make sure to update structure files and  
index files if you store only a part of your system.

however I centred the the chains using gmx trjconv without any error.

Thank you  
Best Regards

Veeru

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<div class="post-metadata">

**Author:** ![alevilla](https://dub1.discourse-cdn.com/flex017/user_avatar/gromacs.bioexcel.eu/alevilla/32/439_2.png) [@alevilla](https://gromacs.bioexcel.eu/u/alevilla)\
**Post date:** [June 11, 2021, 12:18pm UTC](https://gromacs.bioexcel.eu/t/gmx-covar-range-checking-error/2245/2 "2021-06-11T12:18:27Z")

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Hi  
there was a bug on gmx covar that was fix 2021.1  
[https://manual.gromacs.org/current/release-notes/2021/2021.1.html](https://manual.gromacs.org/current/release-notes/2021/2021.1.html)  
you can try to update your version to 2021.2  
\Alessandra