# Problem in running MMPBSA on Gromacs 2020.3

**URL:** <https://gromacs.bioexcel.eu/t/problem-in-running-mmpbsa-on-gromacs-2020-3/3644>\
**Category:** User discussions\
**Tags:** analysis-tools\
**Created:** [February 10, 2022, 11:41am UTC](https://gromacs.bioexcel.eu/t/problem-in-running-mmpbsa-on-gromacs-2020-3/3644 "2022-02-10T11:41:54Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![ladimafakher](https://avatars.discourse-cdn.com/v4/letter/l/cc9497/32.png) [@ladimafakher](https://gromacs.bioexcel.eu/u/ladimafakher)\
**Post date:** [February 10, 2022, 11:41am UTC](https://gromacs.bioexcel.eu/t/problem-in-running-mmpbsa-on-gromacs-2020-3/3644/1 "2022-02-10T11:41:54Z")

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GROMACS version:2020.3  
GROMACS modification: No  
Hello  
I want to run MMPBSA on Gromacs 2020.3 but I got the fatal error in reading tpx file due to incompatible between MMPBSA and Gromacs version while I did not have this error on Gromacs2018. how can I convert od modify my tpx file to analysis MMPBSA on this version of Gromacs.  
thanks for helping me in this issue

 ![Screenshot 2022-02-10 00.37.31](https://europe1.discourse-cdn.com/flex017/uploads/bioexcel1/original/2X/d/d9c3df94076ed5548dbc82728746bc8f7b1d554b.png)

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**Author:** ![jalemkul](https://dub1.discourse-cdn.com/flex017/user_avatar/gromacs.bioexcel.eu/jalemkul/32/18_2.png) [@jalemkul](https://gromacs.bioexcel.eu/u/jalemkul)\
**Post date:** [February 11, 2022, 7:33pm UTC](https://gromacs.bioexcel.eu/t/problem-in-running-mmpbsa-on-gromacs-2020-3/3644/2 "2022-02-11T19:33:01Z")

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You need to re-generate the `.tpr` file with the old version of GROMACS. The developer of `g_mmpbsa` does not keep the code up to date with modern GROMACS versions.

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**Author:** ![ladimafakher](https://avatars.discourse-cdn.com/v4/letter/l/cc9497/32.png) [@ladimafakher](https://gromacs.bioexcel.eu/u/ladimafakher)\
**Post date:** [February 19, 2022, 5:33pm UTC](https://gromacs.bioexcel.eu/t/problem-in-running-mmpbsa-on-gromacs-2020-3/3644/3 "2022-02-19T17:33:46Z")

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Hi  
thanks for your comment. I converted tpr file command “gmx convert-tpr” with the Gromacs version which is compatible with MMPBSA but I got this error"fatal Error: reading tpx file(md\_0\_1.tpr) version 116 with version 83 program" what should I do?

 ![Screenshot 2022-02-10 00.37.31](https://europe1.discourse-cdn.com/flex017/uploads/bioexcel1/original/2X/d/d9c3df94076ed5548dbc82728746bc8f7b1d554b.png)

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**Author:** ![jalemkul](https://dub1.discourse-cdn.com/flex017/user_avatar/gromacs.bioexcel.eu/jalemkul/32/18_2.png) [@jalemkul](https://gromacs.bioexcel.eu/u/jalemkul)\
**Post date:** [February 20, 2022, 2:42am UTC](https://gromacs.bioexcel.eu/t/problem-in-running-mmpbsa-on-gromacs-2020-3/3644/4 "2022-02-20T02:42:15Z")

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You need to completely regenerate the `.tpr` file using `grompp` from the same version as the MM/PBSA utility, which appears to be 4.6.7.

In the future, please paste text from the terminal; screenshots are very hard to read.

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**Author:** ![scinikhil](https://dub1.discourse-cdn.com/flex017/user_avatar/gromacs.bioexcel.eu/scinikhil/32/3483_2.png) [@scinikhil](https://gromacs.bioexcel.eu/u/scinikhil)\
**Post date:** [February 20, 2022, 6:59am UTC](https://gromacs.bioexcel.eu/t/problem-in-running-mmpbsa-on-gromacs-2020-3/3644/5 "2022-02-20T06:59:40Z")

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version 5.1 will support gmx\_mmmpbsa