Attempt to issue a Let’s Encrypt SSL certificate for a Plesk domain fails: Could not obtain directory: cURL error 77

Symptoms

• Plesk Obsidian running on a Centos 7 Linux server
• An attempt to issue a Let's Encrypt SSL certificate for a Plesk domain fails
• The following warning is visible once you go to Plesk > Extensions

  external server error Retry

• The /var/log/plesk/panel.log contains errors that are similar to the following:

  [2023-10-27 11:38:50.436] 36242:653ba14922e7a ERR [extension/sslit] Failed to load ssl config data: Could not get Mozilla tls config: cURL error 77: (see https://curl.haxx.se/libcurl/c/libcurl-errors.html)
  [2023-10-27 11:38:50.788] 36242:653ba14922e7a ERR [panel] Could not get Mozilla tls config: cURL error 77: (see https://curl.haxx.se/libcurl/c/libcurl-errors.html)
  [2023-10-27 11:39:08.365] 36240:653ba15bece48 ERR [extension/sslit] Error happened while certificate processing : <span class='plesk-ext-letsencrypt--ui-problem-adviser-acme-client-request-networking-error' hidden></span>Could not issue a Let's Encrypt SSL/TLS certificate for <b>example.com</b>.
  <br/>
  <br/>Failed to connect to the Let's Encrypt server <i>https://acme-v02.api.letsencrypt.org</i>.
  <br/>Please try again later or report the issue to support.
  <br/><span class='plesk-ext-letsencrypt--details-toggler' data-details-content-id='plesk-ext-letsencrypt--details-content-m1jrHZLHwZ4ra1a3' onclick='PleskExt.Letsencrypt.toggleCollapsibleDetails(this); return false;'>Details</span><div class='plesk-ext-letsencrypt--details-content' id='plesk-ext-letsencrypt--details-content-m1jrHZLHwZ4ra1a3' style='display: none'>Could not obtain directory: cURL error 77: (see https://curl.haxx.se/libcurl/c/libcurl-errors.html) for <a href="https://acme-v02.api.letsencrypt.org/directory
  ">https://acme-v02.api.letsencrypt.org/directory</div><br/>

• There has been a recent update of CentOS 7 NSS packages on this server
• A Plesk Obsidian update to version 18.0.56 Update 2 was performed very recently
• The Plesk > Extensions > My Extensions > SSL It! extension's page is opened with the following error:

  Error: Could not get Mozilla tls config: cURL error 77: (see https://curl.haxx.se/libcurl/c/libcurl-errors.html)

Cause

The combination of updated operating system NSS packages and corrupted Plesk catalog cache is preventing the SSL It! extension from issuing SSL certificates.

Resolution

In order to resolve the issue, you should follow these steps:

1. Connect to the server via SSH

2. Install all available updates within the current Plesk version by executing the following command:

# plesk installer install-all-updates

3. Remove the Plesk catalog cache files:

# rm -rf /usr/local/psa/var/cache/https*

4. Create Plesk database backup (just in case) via the following command:

# plesk db dump > /root/psa_dump"$(date -I)".sql

5. Remove cache records from the Plesk database by executing this command:

# plesk db "delete from PersistentCache where events like '%catalog%'"

6. Restart the Plesk engine service via the following command:

# systemctl restart sw-engine

Once this is done, you should be able to issue Let's Encrypt SSL certificates without issues

Additional information

Plesk domains and various actions like updating WordPress plugins do not work under CentOS 7: cURL error 77 – Plesk

Plesk Updates | Updating Plesk Manually via the Command Line | Plesk Obsidian documentation…