Today I experienced a cryptic error message in my Let’s Encrypt logs about a failing certificate renewal on a customer-facing demo VPS running Ubuntu. The issue looked like a directory or file permissions problem because the Let’s Encrypt certbot couldn’t access a temporary random file it creates on the site so the certificate server can verify the URL.
The certificate renewal failure error messages include the recommendation:
To fix these errors, please make sure that your domain name was entered correctly and the DNS A/AAAA record(s) for that domain contain(s) the right IP address.
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