🔒 SSL / TLS errors

SSL/TLS certificate errors — Let’s Encrypt, name mismatches, chains, PEM files and protocol problems.

CodeErrorWhat it means
Challenge failed for domain Let’s Encrypt / Certbot: Challenge failed for domain example.com — Invalid response from http://example.com/.well-known/acme-challenge/x: 404 Let’s Encrypt couldn’t verify you control the domain — the HTTP-01 challenge file wasn’t served, or DNS point…
NET::ERR_CERT_COMMON_NAME_INVALID NET::ERR_CERT_COMMON_NAME_INVALID: Your connection is not private (certificate is for a different domain) The certificate presented doesn’t include the hostname you visited — e.g. visiting www.example.com with a cer…
no start line OpenSSL: unable to load certificate / PEM routines:get_name:no start line (key values mismatch) OpenSSL (or Nginx/Apache) couldn’t read the certificate or key — wrong file format, wrong file, or the key do…