I too received the following mail:
Action is required to prevent your Let’s Encrypt certificate renewals from breaking.
Your Let’s Encrypt client used ACME TLS-SNI-01 domain validation to issue a certificate in the past 60 days.
TLS-SNI-01 validation is reaching end-of-life and will stop working on February 13th, 2019.
You need to update your ACME client to use an alternative validation method (HTTP-01, DNS-01 or TLS-ALPN-01) before this date or your certificate renewals will break and existing certificates will start to expire.
If you need help updating your ACME client, please open a new topic in the Help category of the Let’s Encrypt community forum:
Please answer all of the questions in the topic template so we can help you.
For more information about the TLS-SNI-01 end-of-life please see our API announcement:
Let’s Encrypt Staff
I ran this command:
It produced this output:
Succeded on all domains.
My web server is (include version):
The operating system my web server runs on is (include version):
Ubuntu 14.04.4 LTS
My hosting provider, if applicable, is:
I can login to a root shell on my machine (yes or no, or I don’t know):
I’m using a control panel to manage my site (no, or provide the name and version of the control panel):
The version of my client is (e.g. output of
certbot --version or
certbot-auto --version if you’re using Certbot):