{"id":2252,"date":"2026-10-13T05:06:48","date_gmt":"2026-10-12T21:06:48","guid":{"rendered":"https:\/\/www.gxcom.net\/"},"modified":"2026-10-13T05:06:48","modified_gmt":"2026-10-12T21:06:48","slug":"lets-encrypt-auto-renewal-failed","status":"publish","type":"post","link":"https:\/\/www.gxcom.net\/zh\/lets-encrypt-auto-renewal-failed\/","title":{"rendered":"Let\u2019s Encrypt SSL \u81ea\u52a8\u7eed\u671f\u5931\u8d25\uff1a\u5982\u4f55\u8bca\u65ad\u548c\u89e3\u51b3"},"content":{"rendered":"

Did your Let's Encrypt SSL auto-renewal fail<\/strong>? An expired certificate can trigger browser security warnings, interrupt HTTPS connections, and undermine visitor trust.<\/p>\n

Common causes include failed ACME challenges, incorrect DNS records, blocked ports, broken Certbot scheduling, and web server configuration errors.<\/p>\n

This guide explains how to diagnose Let's Encrypt renewal failures, restore certificate automation, and prevent future expiration problems.<\/p>\n

\"Let's<\/p>\n

Why Does Let's Encrypt Auto-Renewal Fail?<\/h2>\n

Let's Encrypt certificates have a limited validity period and must be renewed before expiration. Renewal automation depends on your ACME client, domain validation, server configuration, and certificate deployment process.<\/p>\n

\u7b80\u7b54\uff1a<\/strong> Check the certificate's expiration date, run a renewal test, inspect validation errors, verify DNS and network access, and confirm the renewal scheduler is working.<\/p>\n

Do not repeatedly request new certificates without identifying the cause. Unnecessary retries can trigger certificate authority rate limits.<\/p>\n

Common Let's Encrypt Renewal Errors<\/h2>\n\n\n\n\n\n\n\n\n\n\n
Error<\/th>\nLikely Cause<\/th>\n\u9700\u8981\u68c0\u67e5\u7684\u5185\u5bb9<\/th>\n<\/tr>\n<\/thead>\n
Unauthorized<\/td>\nACME challenge validation failed<\/td>\nHTTP response and challenge path<\/td>\n<\/tr>\n
Connection refused<\/td>\nOrigin service or port unavailable<\/td>\nFirewall and web server<\/td>\n<\/tr>\n
DNS problem<\/td>\nIncorrect or missing DNS records<\/td>\nA, AAAA, or TXT records<\/td>\n<\/tr>\n
Timeout<\/td>\nNetwork or routing failure<\/td>\nExternal connectivity<\/td>\n<\/tr>\n
Rate limited<\/td>\nToo many qualifying requests<\/td>\nACME client errors and limits<\/td>\n<\/tr>\n
Deployment failure<\/td>\nCertificate not applied correctly<\/td>\nRenewal hooks and server reload<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

1. Check SSL Certificate Expiration<\/h2>\n

First, determine whether the certificate is expired, approaching expiration, or still valid.<\/p>\n

On Linux, you can inspect a certificate file with OpenSSL:<\/p>\n

openssl x509 -in \/path\/to\/fullchain.pem -noout -dates<\/code><\/pre>\n
Replace the example path with your actual certificate location.<\/p>\n
To inspect the certificate presented by a live website, use:<\/p>\n
openssl s_client -connect example.com:443 -servername example.com <\/dev\/null 2>\/dev\/null | openssl x509 -noout -dates<\/code><\/pre>\n
This helps distinguish a renewal failure from a deployment problem where the server still presents an older certificate.<\/p>\n
2. Run a Certbot Renewal Test<\/h2>\n
If your server uses Certbot, run a simulated renewal:<\/p>\n
sudo certbot renew --dry-run<\/code><\/pre>\n
This tests the renewal configuration without replacing your production certificate in the normal workflow.<\/p>\n
Review the output for challenge failures, authentication errors, missing files, or permission problems.<\/p>\n
You can also list certificates managed by Certbot:<\/p>\n
sudo certbot certificates<\/code><\/pre>\n
\u91cd\u8981\u63d0\u793a\uff1a<\/strong> These commands apply to Certbot installations. Hosting control panels and other ACME clients may use different renewal mechanisms.<\/p>\n
3. Fix HTTP-01 Challenge Failures<\/h2>\n
HTTP-01 validation requires the certificate authority to retrieve a challenge resource from your domain over HTTP on port 80.<\/p>\n
Verify that the domain resolves to the correct server and that inbound TCP port 80 is reachable from the public internet.<\/p>\n
Also inspect redirects, reverse proxy rules, firewall policies, and security tools that may block requests to:<\/p>\n
\/.well-known\/acme-challenge\/<\/code><\/pre>\n
Redirects are not automatically a problem, but unsupported redirect destinations or incorrect routing can cause validation failures.<\/p>\n
If port 80 cannot be made available, consider an appropriate DNS-01 validation method instead.<\/p>\n
4. Check DNS Records and DNS-01 Validation<\/h2>\n
Incorrect DNS records can send validation requests to the wrong server.<\/p>\n
Inspect public A and AAAA records:<\/p>\n
dig example.com A +short\r\ndig example.com AAAA +short<\/code><\/pre>\n
If your domain has an AAAA record, verify that the IPv6 destination is configured correctly.<\/p>\n
For DNS-01 validation, the ACME client must create or verify the required TXT record under the appropriate _acme-challenge<\/code> name.<\/p>\n
DNS propagation, API permissions, or incorrect credentials may cause DNS-01 renewals to fail.<\/p>\n
5. Verify Certbot Automatic Renewal Scheduling<\/h2>\n
A successful manual renewal does not guarantee that scheduled renewal works.<\/p>\n
Depending on installation method, Certbot may use a systemd timer, cron job, or another scheduling mechanism.<\/p>\n
On systems using a Certbot systemd timer, check:<\/p>\n
systemctl list-timers --all | grep certbot<\/code><\/pre>\n
For relevant logs, try:<\/p>\n
sudo journalctl -u certbot.service<\/code><\/pre>\n
Service names and log locations vary. Snap packages, hosting panels, and custom installations may behave differently.<\/p>\n
Confirm that the scheduled task actually executes and reports successful renewals.<\/p>\n
6. Check Nginx, Apache, and Certificate Deployment<\/h2>\n
Sometimes renewal succeeds, but the web server continues serving an older certificate.<\/p>\n
Check whether your web server references the correct certificate files and whether the deployment hook reloads the service.<\/p>\n
Before applying changes, validate the configuration:<\/p>\n
sudo nginx -t<\/code><\/pre>\n
For Apache on supported systems:<\/p>\n
sudo apachectl configtest<\/code><\/pre>\n
Only reload services after confirming that the configuration is valid.<\/p>\n
If the issue involves broader server administration, see our \u6258\u7ba1\u578b\u4e0e\u975e\u6258\u7ba1\u578b\u4e3b\u673a\u6307\u5357<\/a>.<\/p>\n
7. Check Firewall, CDN, and Reverse Proxy Settings<\/h2>\n
A CDN, reverse proxy, or web application firewall may interfere with ACME validation if challenge requests are blocked or routed incorrectly.<\/p>\n
Confirm that the validation method matches your network architecture.<\/p>\n
For HTTP-01, the certificate authority must be able to reach the correct challenge response. For DNS-01, DNS record creation and visibility are essential.<\/p>\n
Do not permanently disable security controls just to complete renewal. Correct the validation routing or authentication configuration.<\/p>\n
How to Prevent Future SSL Renewal Failures<\/h2>\n