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Cannot issue wildcard Let's Encrypt certificate in Plesk: DNS problem: NXDOMAIN looking up TXT for _acme-challenge.example.com

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Taras Ermoshin
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Plesk for Windows Plesk for Linux kb: technical ext: le ABT: Group A

Applicable to:

  • Plesk for Linux
  • Plesk for Windows

Symptoms

  • Issuing a wildcard Let's Encrypt certificate in Plesk in Domains > example.com > Let's Encrypt (or in Domains > example.com > SSL/TLS Certificates if the extension SSL It! is installed) fails with the error:

    PLESK_ERROR: Error: Could not issue a Let's Encrypt SSL/TLS certificate for example.com. Authorization for the domain failed.
    Details
    Invalid response from https://acme-v02.api.letsencrypt.org/acme/authz/zEHPSbB4eUyIomzu9qynFouNGrIgiUlJZ755z_Kx4kY.
    Details:
    Type: urn:ietf:params:acme:error:dns
    Status: 400
    Detail: DNS problem: NXDOMAIN looking up TXT for _acme-challenge.example.com

  • The TXT DNS record for the hostname _acme-challenge.example.com is not available globally:

    # nslookup -type=TXT _acme-challenge.example.com
    Server: 8.8.8.8
    Address: 8.8.8.8#53

    ** server can't find _acme-challenge.example.com: NXDOMAIN

  • The same DNS record is present in Plesk in Domains > example.com > DNS Settings and is returned by Plesk's DNS server:

    # nslookup -type=TXT _acme-challenge.example.com example.com
    Server: example.com
    Address: 203.0.113.2#53

    _acme-challenge.example.com text = "yFHaUBDo0THtVyjdmtwmJkgEAmPDemtITjpftHrN9Wg"

Cause

The TXT DNS record for the hostname _acme-challenge.example.com is not available globally.

Resolution

DNS zone of the domain is hosted on the Plesk server

  1. Wait until the DNS propagation is completed and the required record is available globally. The propagation can take up to 72 hours. Check of the record's availability can be done on resources like https://dnschecker.org/.

  2. Issue Let's Encrypt certificate again in Plesk in Domains > example.com > Let's Encrypt (or in Domains > example.com > SSL/TLS Certificates).

DNS zone of the domain is hosted on external DNS hosting

  1. On the external DNS hosting, add the TXT record for the hostname _acme-challenge.example.com. The value for the record can be obtained in Plesk in Domains > example.com > DNS Settings.

  2. Issue Let's Encrypt certificate again in Plesk in Domains > example.com > Let's Encrypt (or in Domains > example.com > SSL/TLS Certificates).

Comments

3 comments

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  • Avatar
    Alex Laforge

    Having to specifiy the TXT content on the external Name Server each time a renew is required is absolutely impossible, too long, so not a solution.

    We definitely NEED an option in Plesk Obsidian Windows to be able to choose if :

    - Option A : Plesk Let's Encrypt extension will use the method of adding a TXT record in the Plesk DNS Zone

    - Option B : Plesk Let's Encrypt extension will use the method of creating a /.well-known/ file under the domain root. This option will be useful for all the people not using Plesk as their Name Server.

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  • Avatar
    Lev Iurev

    @Alex Laforge As I can see it was figured out in the ticket.

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  • Avatar
    Alex Laforge

    Yes, your technical support solved the situation. In fact, for those who come to this page, you must know that, to issue certificates, Let's Encrypt servers use two types of challenges:

    • HTTP-01 for issuing regular certificates - the token is checked at the URL http://<YOUR_DOMAIN>/.well-known/acme-challenge/<TOKEN>.
    • DNS-01 for issuing wildcard certificates - the token is checked in the DNS TXT record _acme-challenge.<YOUR_DOMAIN>.

    More information are available at this page https://letsencrypt.org/docs/challenge-types/

    I wish that this information would be more clearly displayed inside Plesk, or on the SSL-related Plesk Documentation pages.

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