# Error EXT \[Making and trusting your own certificates\]

**URL:** <https://community.letsencrypt.org/t/error-ext-making-and-trusting-your-own-certificates/120333>\
**Category:** Help\
**Created:** [April 22, 2020, 6:41am UTC](https://community.letsencrypt.org/t/error-ext-making-and-trusting-your-own-certificates/120333 "2020-04-22T06:41:44Z")\
**Posts on this page:** 1\
**Showing post:** 3

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**Author:** ![JuergenAuer](https://sea3.discourse-cdn.com/letsencrypt/user_avatar/community.letsencrypt.org/juergenauer/32/26491_2.png) [@JuergenAuer](https://community.letsencrypt.org/u/JuergenAuer)\
**Post date:** [April 22, 2020, 6:45am UTC](https://community.letsencrypt.org/t/error-ext-making-and-trusting-your-own-certificates/120333/3 "2020-04-22T06:45:36Z")

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Hi @JNB_Dimo

> [@JNB\_Dimo](#):
>
> \<(printf

that's a Unix command, I don't think that works on Windows.

> [@JNB\_Dimo](#):
>
> -extensions EXT

Looks like try and error. Check the documentation of your OpenSsl.

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