How to add a subdomain to an existing certificate using certbot

You’re probably reading this because you already have a Let’s Encrypt certificate issued using certbot for a domain, and now want to add-on subdomains.

If you want to create a new certificate, have a look at the end of this article.

In my case I already had a certificate which covered


I have a directory on my server called dev that I want to reference via

So to do that, I issued the following command

certbot -d,, --expand

Key takeaways:

  1. re-include every domain name you want on that certificate again. I forgot www. the first time. No biggie, just re-run with all the domains you want.
  2. don’t forget to add --expand to the end

After reading around on the net a bit, I found this solution on this GitHub thread.

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Andrew Golightly is the lead web developer here at Golightly+. He is a passionate fullstack JavaScript developer. He also runs an Empath Community.

8 thoughts on “How to add a subdomain to an existing certificate using certbot”

  1. Very simple and effective!
    Thank you so much. :))

    I thought it was going to be a bigger struggle. 🤣

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