Hey there, sorry to hear you're hitting that "Get Authorization fail" roadblock when trying to set up your Let's Encrypt certificate. I've dealt with this issue a few times, so let's go through some practical troubleshooting steps that usually get things sorted:

• Double-check your domain's DNS setup
  First off, make sure your domain is resolving to the correct server IP. Grab your terminal and run nslookup yourdomain.com or dig yourdomain.com to confirm. If the DNS records are wrong, or they haven't finished propagating (this can take up to 24 hours), Let's Encrypt won't be able to find your server to validate the domain.

• Ensure your server is publicly accessible
  Let's Encrypt needs to reach your server on either port 80 (for the HTTP-01 challenge) or port 443 (for TLS-ALPN-01). Verify that:

  • Your firewall isn't blocking incoming traffic on these ports—double-check both server-side firewalls and any cloud security groups you might have set up.
  • There's no misconfigured CDN, proxy, or VPN that's preventing external access to your server.
  • You can load http://yourdomain.com from a device outside your local network (not just your own computer).

• Validate the HTTP-01 challenge file setup
  If you're using the HTTP-01 challenge, Let's Encrypt will attempt to access a unique file at http://yourdomain.com/.well-known/acme-challenge/[random-string]. Make sure:

  • Your web server (Apache, Nginx, etc.) is configured to serve files from the .well-known/acme-challenge directory without redirects. For example, if you have an HTTP-to-HTTPS redirect enabled, it might interfere with the challenge—temporarily disable it if needed.
  • The challenge file has the correct permissions so your web server can read and serve it (usually 644 for files, 755 for directories).

• Check for Let's Encrypt rate limits
  Let's Encrypt enforces rate limits to prevent abuse. If you've tried generating certificates multiple times in a short window, you might have hit a limit. Run certbot certificates (if you're using Certbot) to check your current usage, or look for rate limit warnings in your ACME client logs.

• Dig into your ACME client logs
  Most tools like Certbot keep detailed logs that spell out exactly why the authorization failed. For Certbot, logs are usually in /var/log/letsencrypt/letsencrypt.log. Look for specific errors like connection timeouts, DNS lookup failures, or invalid challenge responses—these will give you a clear clue about what's broken.

• Try switching to the DNS-01 challenge
  If the HTTP challenges keep failing, the DNS-01 method might be more reliable, especially if you have a complex network setup (like load balancers or CDNs). This requires adding a TXT record to your domain's DNS settings with a specific value provided by your ACME client. Once the record propagates, Let's Encrypt will validate it without needing to reach your web server directly.

内容的提问来源于stack exchange，提问作者Alice