Secure your Azure Web App using SSL Certificate provided by Let’s Encrypt

Written by ppolyzos

Software engineer based in beautiful Luxembourg


  1. Diego

    I have followed your tutorial step by step but, unfortunately, I have an error at the end of step 4 “Request and install certificate”.

    The error is:
    Server Error in ‘/letsencrypt’ Application.
    Response status code does not indicate success: 403 (Forbidden).

    I required a certificate for a second level domain like
    I faced the same error creating the certificate on my machine and trying to upload it on Azure.
    Any suggestion?
    With the first level domain like, I had no problem

    Thanks in advance,

    1. ppolyzos

      For subdomains you need to repeat the process and you will see the subdomain in the `hostnames` list, as shown in the last picture of step 4.
      Sometimes, it takes some time between new domain assignments, however I am not sure if that’s the issue in your case.
      Are you trying to add a slot in the same web app or are you creating a different web app?

  2. Diego

    I saw my subdomain in the hostnames list and I have used it to go ahead. I have tried again but same error occured.

    My subdomain is hosted in a separated web app, I can’t use a slot to do a test because the first level domain is my production. Do you think using the same web app it can work? Why?


    1. ppolyzos

      Nope, I don’t think that the problem.
      Let’s try a few more things:
      1. Can you do a restart from
      2. Can you check that you have assigned permissions to the resource group?

      1. Diego

        below my answers:
        1 – Done. I have used that page to restart the app for the previous test
        2 – Yes, I have owner permissions to the resource group

        1. ppolyzos

          And I guess the app service plan is in the same resource group that you have given owner permissions.
          And you have created the service principal with the same subscription that your app service and web app are using.

          I would suggest to open a support ticket to further help you and check what exactly is happening in your case.

          1. Diego

            Yes, you are right, I have all the required permissions but, unfortunately,
            it still not work.

            Thanks a lot for your support, I’m going to open a support ticket.

            Best regards,

  3. Jenny

    I completed the tutorial successfully, thanks for that!
    So my certificate now expires in 2 months. So what are the steps to update it? Or will it be automatically updated?

    1. ppolyzos

      Usually, it gets updated automatically. Otherwise, you ‘ll get an email warning you that your certificate is about to expire and you need to follow some very simple steps so to update it.

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