# 'topol' does not exist or is not accessible

**URL:** <https://gromacs.bioexcel.eu/t/topol-does-not-exist-or-is-not-accessible/6087>\
**Category:** User discussions\
**Tags:** mdrun, energy-minization\
**Created:** [April 1, 2023, 7:53pm UTC](https://gromacs.bioexcel.eu/t/topol-does-not-exist-or-is-not-accessible/6087 "2023-04-01T19:53:11Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![MinhaSakib](https://avatars.discourse-cdn.com/v4/letter/m/46a35a/32.png) [@MinhaSakib](https://gromacs.bioexcel.eu/u/MinhaSakib)\
**Post date:** [April 1, 2023, 7:53pm UTC](https://gromacs.bioexcel.eu/t/topol-does-not-exist-or-is-not-accessible/6087/1 "2023-04-01T19:53:11Z")

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

Hi guys,  
During the simulation of a peptide, I am facing the following error: How can i solve it ?

GROMACS: gmx mdrun, VERSION 5.1.2  
Executable: /opt/gromacs/bin/gmx  
Data prefix: /opt/gromacs  
Command line:  
gmx mdrun -deffnm nvt-pr

* * *

Program: gmx mdrun, VERSION 5.1.2  
Source file: src/gromacs/options/options.cpp (line 248)  
Function: void gmx::Options::finish()

Error in user input:  
Invalid input values  
In option s  
Required option was not provided, and the default file ‘topol’ does not  
exist or is not accessible.  
The following extensions were tried to complete the file name:  
.tpr

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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:** [April 2, 2023, 2:32am UTC](https://gromacs.bioexcel.eu/t/topol-does-not-exist-or-is-not-accessible/6087/2 "2023-04-02T02:32:52Z")

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There is no such file called “nvt-pr.tpr” in the working directory, and `mdrun` also cannot find the default file name “topol.tpr” so it is bailing out.

Also, it is wise to use a newer version of GROMACS. Version 5.1.2 is absolutely ancient and no longer supported.

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**Author:** ![Mobina](https://avatars.discourse-cdn.com/v4/letter/m/f04885/32.png) [@Mobina](https://gromacs.bioexcel.eu/u/Mobina)\
**Post date:** [December 6, 2025, 11:30am UTC](https://gromacs.bioexcel.eu/t/topol-does-not-exist-or-is-not-accessible/6087/3 "2025-12-06T11:30:50Z")

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Hi, this error will appear if the name of the .tpr file is not the same as the output file of the mdrun command.