# How to fix 'no such molecule type SOL'

**URL:** <https://gromacs.bioexcel.eu/t/how-to-fix-no-such-molecule-type-sol/2808>\
**Category:** User discussions\
**Tags:** grompp\
**Created:** [September 13, 2021, 8:41pm UTC](https://gromacs.bioexcel.eu/t/how-to-fix-no-such-molecule-type-sol/2808 "2021-09-13T20:41:41Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![gloria](https://avatars.discourse-cdn.com/v4/letter/g/b38774/32.png) [@gloria](https://gromacs.bioexcel.eu/u/gloria)\
**Post date:** [September 13, 2021, 8:41pm UTC](https://gromacs.bioexcel.eu/t/how-to-fix-no-such-molecule-type-sol/2808/1 "2021-09-13T20:41:41Z")

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I’m reproducing this tutorial [Lysozyme in Water](http://www.mdtutorials.com/gmx/lysozyme/04_ions.html) with a different protein.

During the generation of the .tpr file for the step of adding ions, I’m getting this error: ‘No such molecule type SOL.’ After adding the SOL to the molecule type section, I get the ‘molecule type protein has no atoms’ error.

My protein has a covalently bonded cofactor, so I’ve used AMBER files () for the generation of GMX.top and protein.gro files and started the tutorial from the ‘define box and solvent’ step.

I’m providing relevant parts of the topology file:  
…

[moleculetype]  
;name nrexcl  
protein 3  
…  
[system]  
protein in water

[molecules]  
; Compound nmols  
protein 1  
SOL 53832

Any help is appreciated!

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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:** [September 14, 2021, 5:17pm UTC](https://gromacs.bioexcel.eu/t/how-to-fix-no-such-molecule-type-sol/2808/2 "2021-09-14T17:17:14Z")

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Please post this question in the User Forum, not Site Feedback. You should attach your complete topology file.