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‘Unable to renew certificate: The Let’s Encrypt HTTP challenge failed’

This article was written to help you troubleshoot/resolve the below error received from Let’s Encrypt:

‘Unable to renew certificate: The Let’s Encrypt HTTP challenge failed: acme error ‘urn:acme:error:unauthorized’

It is possible you are receiving this error for any of the following reasons:

1. Permissions Issue: Let’s Encrypt potentially doesn’t have the correct permissions to access the required directories/files. You can check your permissions via the File Manager function in cPanel or using an FTP client.

Within your public_html directory, make sure that the files  /.well-known and ./well-known/acme-challenge both have the permission set 755.

2. Conflicting Redirect Rule: Make sure that there isnt a conflicting redirect rule adjusting your URL structure. Usually you can identify your configured redirects by viewing your .htaccess file.

To resolve this, you could add an exception so Let’s Encrypt can access .well-known, this can be achieved by adding an entry like below into your .htaccess file:

# Allow .well-known through for Let's Encrypt.
RewriteCond %{REQUEST_URI} !^/\.well\-known/acme\-challenge/

Please be aware that the build of every website is different so although this code has worked for our support team previously, it has not always been successful. Serversaurus is not responsible for any unwanted interaction, it is up to you or your developer to understand how this code will interact with your website and if needed adjust to be compatible with your website.

3. Domain is hosted externally: You are not able to issue a certificate for a domain that is hosted externally. Review which domains you are trying to issue the certificate for, if your website is hosted with Serversaurus but your mail services is hosted elsewhere, you will have to remove mail.yourdomain.com from the certificate.

If needed update the domains included in your certificate before re-attempting to issue the certificate.


Hopefully after following these steps you will have identified where the issue was and resolved the error. If issues persist you may need to consider discussing this issue with the person who built the site and has a deeper understanding of the website functionality.

Updated on November 29, 2018

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