# Unexpected error: cannot instantiate ctype 'EVP\_MD\_CTX' of unknown size

**URL:** <https://community.letsencrypt.org/t/unexpected-error-cannot-instantiate-ctype-evp-md-ctx-of-unknown-size/41284>\
**Category:** Help\
**Created:** [August 31, 2017, 9:35am UTC](https://community.letsencrypt.org/t/unexpected-error-cannot-instantiate-ctype-evp-md-ctx-of-unknown-size/41284 "2017-08-31T09:35:46Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![richardfoley](https://sea3.discourse-cdn.com/letsencrypt/user_avatar/community.letsencrypt.org/richardfoley/32/15796_2.png) [@richardfoley](https://community.letsencrypt.org/u/richardfoley)\
**Post date:** [August 31, 2017, 9:35am UTC](https://community.letsencrypt.org/t/unexpected-error-cannot-instantiate-ctype-evp-md-ctx-of-unknown-size/41284/1 "2017-08-31T09:35:46Z")

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hi folks, I created a certificate (which works and is secure) using the following command:

> certbot --apache --keep -d [www.rfi.net](http://www.rfi.net)

When I run a check on it, using "certbot certificates" I get:

> Renewal configuration file /etc/letsencrypt/renewal/rfi.net.conf produced an unexpected error: cannot instantiate ctype 'EVP\_MD\_CTX' of unknown size. Skipping

This doesn't look good for the next renewal attempt... Any ideas?

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**Author:** ![jared.m](https://sea3.discourse-cdn.com/letsencrypt/user_avatar/community.letsencrypt.org/jared.m/32/17871_2.png) [@jared.m](https://community.letsencrypt.org/u/jared.m)\
**Post date:** [August 31, 2017, 1:36pm UTC](https://community.letsencrypt.org/t/unexpected-error-cannot-instantiate-ctype-evp-md-ctx-of-unknown-size/41284/2 "2017-08-31T13:36:20Z")

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My best idea would be working with some of your Python dependencies as suggested here: [https://github.com/burnash/gspread/issues/407](https://github.com/burnash/gspread/issues/407)

However that’s just from some quick poking around, so definitely vet those results against your environment.

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**Author:** ![richardfoley](https://sea3.discourse-cdn.com/letsencrypt/user_avatar/community.letsencrypt.org/richardfoley/32/15796_2.png) [@richardfoley](https://community.letsencrypt.org/u/richardfoley)\
**Post date:** [August 31, 2017, 3:09pm UTC](https://community.letsencrypt.org/t/unexpected-error-cannot-instantiate-ctype-evp-md-ctx-of-unknown-size/41284/3 "2017-08-31T15:09:27Z")

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thanks for the response, Jared. I tried this:

> pip install cryptography==1.4

and got various compilation areas. I've a fairly clean Debian 9 (Stretch) install. Working my way through the missing libs, and installing: libffi-dev, gcc got me to the point where running the pip command above worked cleanly, and apparently I've successfully cargo-culted my cryptography to v1.4 Now when I run "certbot certificates" I get a meaningful output:

> Saving debug log to /var/log/letsencrypt/letsencrypt.log
> 
> * * *
> 
> Found the following certs:  
> Certificate Name: [rfi.net](http://rfi.net)  
> Domains: [rfi.net](http://rfi.net),[pub.rfi.net](http://pub.rfi.net),[www.rfi.net](http://www.rfi.net)  
> Expiry Date: 2017-11-29 08:45:00+00:00 (VALID: 89 days)  
> ...

So I think this looks good. Many thanks for the tip! 😀

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**Author:** ![system](https://global.discourse-cdn.com/letsencrypt/original/3X/c/a/ca6c06ea1ea201324bba7048c6841ce60236468d.png) [@system](https://community.letsencrypt.org/u/system)\
**Post date:** [September 30, 2017, 3:09pm UTC](https://community.letsencrypt.org/t/unexpected-error-cannot-instantiate-ctype-evp-md-ctx-of-unknown-size/41284/4 "2017-09-30T15:09:29Z")

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