# Error in Installation of gromacs

**URL:** <https://gromacs.bioexcel.eu/t/error-in-installation-of-gromacs/1964>\
**Category:** User discussions\
**Tags:** installation-error\
**Created:** [April 15, 2021, 5:35am UTC](https://gromacs.bioexcel.eu/t/error-in-installation-of-gromacs/1964 "2021-04-15T05:35:04Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![yuvaraj006](https://avatars.discourse-cdn.com/v4/letter/y/a698b9/32.png) [@yuvaraj006](https://gromacs.bioexcel.eu/u/yuvaraj006)\
**Post date:** [April 15, 2021, 5:35am UTC](https://gromacs.bioexcel.eu/t/error-in-installation-of-gromacs/1964/1 "2021-04-15T05:35:04Z")

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GROMACS version: gromacs-2021.1  
GROMACS modification: Yes/No

Dear all  
I am trying to install gromacs, While running the make command, It stops by this error, Error is “Failed to connect to [www.fftw.org](http://www.fftw.org)”.

Even tried to access [www.fftw.org](http://www.fftw.org) through browser, site is not connecting. How to fix this error.

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**Author:** ![pjohansson](https://dub1.discourse-cdn.com/flex017/user_avatar/gromacs.bioexcel.eu/pjohansson/32/316_2.png) [@pjohansson](https://gromacs.bioexcel.eu/u/pjohansson)\
**Post date:** [April 15, 2021, 7:17am UTC](https://gromacs.bioexcel.eu/t/error-in-installation-of-gromacs/1964/2 "2021-04-15T07:17:09Z")

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Hi,

it’s possible that the site which distributes the FFTW library was temporarily unavailable – I can reach it now, so you might want to try again.

In case you still cannot connect to it you can remove `-DGMX_BUILD_OWN_FFTW=on` from your `cmake` command, or set it to `=off`. You will then either need to have an FFTW library installed on your machine, or use a slower library that Gromacs is bundled with called `fftpack`.

See this section of the installation guide for more information on how to proceed: [Fast Fourier Transform library](https://manual.gromacs.org/current/install-guide/index.html#fast-fourier-transform-library)

Regards,  
Petter