403 Forbidden when Registering Certificate


Need some help understanding why I cannot register my certificate. Getting a 403 Forbidden error in the logs, but I can navigate to http://home.geektasticdad.com/.well-known/acme-challenge/configcheck just fine. Any advice would be appreciated.

2018-05-05 21:27:21.816 -07:00 [INF] Performing Config Tests
2018-05-05 21:27:23.296 -07:00 [INF] Beginning Certificate Request Process: Default Web Site
2018-05-05 21:27:23.297 -07:00 [INF] Registering Domain Identifiers
2018-05-05 21:27:23.298 -07:00 [INF] Attempting Domain Validation: home.geektasticdad.com
2018-05-05 21:27:23.300 -07:00 [INF] Registering and Validating home.geektasticdad.com
2018-05-05 21:27:24.587 -07:00 [INF] Performing Challenge Response via IIS: home.geektasticdad.com
2018-05-05 21:27:25.255 -07:00 [INF] Requesting Validation from Let’s Encrypt: home.geektasticdad.com
2018-05-05 21:27:25.998 -07:00 [INF] Domain validation failed: home.geektasticdad.com
[type, urn:acme:error:unauthorized]
[detail, Invalid response from http://home.geektasticdad.com/.well-known/acme-challenge/oWiXYcfl1RbYs17hS4X89h9w49C1PuufU5_lqKWtbe0: "

403 Forbidden


<p"] [status, 403]


The error 403 literally means that Let’s Encrypt was not allowed to ask for the file it’s trying to access.

I assume that when you look in your /.well-known/acme-challenge/ folder you just have the ‘configcheck’ file and a web.config, and not the challenge response file oWiXYcfl1RbYs17hS4X89h9w49C1PuufU5_lqKWtbe0 which has probably been clean up by now.

If you copy or rename the configcheck file to a random name can you still access it in a web browser (using the random name)?

I just wondered if you had a web.config rule in the parent app that allowed configcheck to work, but not other file name combinations (‘configcheck’ is just an easy name for us to test with, but the real challenge gets a random file name with no extension).


I do have the same issue. rn:acme:error:unauthorized 403. Please can you help? I have tried to acces /.well-known/acme-challenge/RANDOMNAME and it is not working… I use IIS.


I was able to resolve this, it was firewall configurations that were preventing connectivity I believe. I use a Sophos XG firewall and had to set up Web Server protection and it was able to get the certificate to generate.


Thank you @geektasticdad. Unfortunately, this is not my case. :frowning:


@mv15 here is some supporting documentation: https://docs.certifytheweb.com/docs/http-validation.html

Your website is specifically denying access to the file. This is usually because the parent application has authentication switched on.

Can you look at your web.config that should be in the /.well-known/acme-challenge of your website? It should have an entry like this, to allow any user to access the folder:

      <allow users="*" />

You may need to add an exception to your parent application web.config like this (the syntax might not be exact but you’ll see the general idea):

   <location path=".well-known/acme-challenge">
            <allow users="*"/>


Thank you @webprofusion, this worked!