This error usually occurs due to outdated or missing SSL certificate files used by WordPress when establishing secure connections.
To resolve the issue, you need to update the certificate bundle used by WordPress:
- Download the latest ca-bundle.crt file from: https://curl.se/ca/cacert.pem
- Upload the downloaded file to the WordPress directory: /wp-includes/certificates/
- Replace the existing ca-bundle.crt file with the new version (you may delete the old file beforehand).
- After replacing the file, run the WordPress update again.
