# Gmx angle Fatal error

**URL:** <https://gromacs.bioexcel.eu/t/gmx-angle-fatal-error/529>\
**Category:** User discussions\
**Created:** [July 20, 2020, 2:58am UTC](https://gromacs.bioexcel.eu/t/gmx-angle-fatal-error/529 "2020-07-20T02:58:47Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![btam125](https://avatars.discourse-cdn.com/v4/letter/b/a88e57/32.png) [@btam125](https://gromacs.bioexcel.eu/u/btam125)\
**Post date:** [July 20, 2020, 2:58am UTC](https://gromacs.bioexcel.eu/t/gmx-angle-fatal-error/529/1 "2020-07-20T02:58:47Z")

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GROMACS version:2020  
GROMACS modification: /No  
Here post your question

Dear all,

I am trying to using GROMACS to do Principle Component Analysis by following this link:

[http://manual.gromacs.org/documentation/2019.4/reference-manual/analysis/dihedral-pca.html](http://manual.gromacs.org/documentation/2019.4/reference-manual/analysis/dihedral-pca.html)

However, when I reach gmx angle, I have this error:

Fatal error: Can not combine angles with trr dump gromacs

I have look through google and cannot find much information of that error, can someone explain how do I solve this?

Best,

Ben