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Let's Encrypt Certificate Renewal Error — Certbot and SSL Auto-Renewal Failures

Errorsecurity

Overview

Fix Let's Encrypt certificate renewal failures in Certbot caused by DNS validation errors, web server conflicts, and automatic renewal cron job issues.

Key Details

  • Let's Encrypt certificates expire every 90 days and must be renewed regularly
  • Certbot handles automatic renewal via a systemd timer or cron job
  • Renewal can fail if the domain validation method (HTTP-01 or DNS-01) is not working
  • HTTP-01 validation requires port 80 to be accessible from the internet
  • Wildcard certificates require DNS-01 validation which needs DNS API access

Common Causes

  • Port 80 blocked by firewall — HTTP-01 validation cannot reach the server
  • Web server configuration changed since initial certificate issuance
  • DNS API credentials expired for DNS-01 (wildcard) validation
  • Certbot renewal hook failing to restart the web server after renewal

Steps

  1. 1Test renewal: 'sudo certbot renew --dry-run' to check if renewal would succeed
  2. 2Check Certbot logs: 'cat /var/log/letsencrypt/letsencrypt.log' for detailed error messages
  3. 3Ensure port 80 is open: 'sudo ufw allow 80/tcp' or check cloud firewall rules
  4. 4Verify the renewal timer: 'systemctl status certbot.timer' or check crontab for certbot renew entry
  5. 5For DNS-01: update DNS API credentials in /etc/letsencrypt/renewal/[domain].conf

Tags

letsencryptcertbotsslcertificaterenewal

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Frequently Asked Questions

Certbot's auto-renewal runs twice daily and renews certificates when they have less than 30 days until expiry. With 90-day certificates, renewal happens roughly every 60 days.