# Fatal error

**URL:** <https://gromacs.bioexcel.eu/t/fatal-error/752>\
**Category:** User discussions\
**Created:** [September 1, 2020, 11:18am UTC](https://gromacs.bioexcel.eu/t/fatal-error/752 "2020-09-01T11:18:21Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![Ponaskillz](https://avatars.discourse-cdn.com/v4/letter/p/ecccb3/32.png) [@Ponaskillz](https://gromacs.bioexcel.eu/u/Ponaskillz)\
**Post date:** [September 1, 2020, 11:18am UTC](https://gromacs.bioexcel.eu/t/fatal-error/752/1 "2020-09-01T11:18:21Z")

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I got the error message below when trying to generate a protein topology file for a protein with the pub code: 3jzk using the pdb2gmx module

> Fatal error:  
> Residue 1 named GLN of a molecule in the input file was mapped to an entry in the topology database, but the atom CG used in that entry is not found in the input file. Perhaps your atom and/or residue naming needs to be fixed

Please I would like some help