Let's Encrypt has become the default SSL solution for Plesk-managed servers — it's free, trusted by all major browsers, and renews automatically. But sysadmins running Plesk servers know the frustration: a certificate that worked fine suddenly stops auto-renewing, or a new domain's SSL install fails with a cryptic DNS validation error.
This guide covers the complete Let's Encrypt setup in Plesk, including the pre-setup DNS checks that prevent most failures, per-domain and wildcard certificate configuration, and the specific troubleshooting steps for the most common auto-renewal failures.
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Get Expert Help →Prerequisites Before Installing Let's Encrypt in Plesk
Skipping these checks is the most common reason Let's Encrypt installations fail. Before clicking anything in Plesk:
Let's Encrypt validates domain ownership by making an HTTP request to your domain. If DNS hasn't propagated yet or points to a different server, the validation will fail. Check DNS resolution before attempting installation:
dig A yourdomain.com @8.8.8.8
dig A www.yourdomain.com @8.8.8.8Both should return your server's IP address. If they don't, wait for DNS propagation before proceeding.
Navigate to Domains > yourdomain.com > Hosting & DNS > Hosting Settings. Enable the "SSL/TLS support" checkbox. Without this, the Let's Encrypt extension cannot install a certificate for the domain.
In Plesk, go to Extensions > My Extensions. Verify "Let's Encrypt" appears in the installed list. If not, install it from Extensions > Extensions Catalog > search "Let's Encrypt."
Let's Encrypt's HTTP challenge requires port 80 to be open and responding. Verify with:
curl -I http://yourdomain.comA redirect or 200 response confirms port 80 is accessible. A connection refused error means a firewall rule is blocking Let's Encrypt's validation crawler.
In Plesk, go to Domains > yourdomain.com > Hosting & DNS > SSL/TLS Certificates. Click the Get it free button in the Let's Encrypt section at the top of the page.
On the Let's Encrypt certificate request form:
- Email address — Enter a valid email for expiry notifications
- Include www subdomain — Check this to cover both
yourdomain.comandwww.yourdomain.com - Include mail subdomain — Check this if your mail server uses this domain (covers
mail.yourdomain.com) - Include webmail subdomain — Check to cover Plesk's webmail interface
Plesk contacts Let's Encrypt's servers, completes the domain validation challenge, and installs the certificate automatically. The process takes 15-60 seconds under normal conditions.
After installation, the SSL/TLS Certificates page should show:
Let's Encrypt [yourdomain.com]
Valid until: [date ~90 days from now]
Auto-renew: EnabledTest the SSL installation with an external checker: navigate to https://yourdomain.com and verify the padlock appears, or use SSL Labs' server test.
Go to Tools & Settings > Mail Server Settings. Under "SSL/TLS certificate for mail," select the Let's Encrypt certificate you just installed for your main domain (if the mail server uses the same hostname as your domain) or install a separate certificate for your mail hostname.
If your server's hostname (e.g., server1.yourdomain.com) is different from your website domain, install a separate Let's Encrypt certificate for it. Go to Tools & Settings > SSL/TLS Certificates (Plesk) and click "Get it free."
Go to Tools & Settings > Scheduled Tasks (System). Look for a task named "Let's Encrypt" or "letsencrypt." It should run daily (or at minimum weekly). If no such task exists, the extension may not be installed correctly — reinstall it from Extensions > My Extensions > Let's Encrypt > Reinstall.
From the Plesk server via SSH, run:
plesk ext letsencrypt --renew-allThis forces Plesk to attempt renewal for all Let's Encrypt certificates. Review the output for errors. Certificates with more than 30 days remaining won't renew (this is intentional behavior — Let's Encrypt only renews within 30 days of expiry).
tail -n 100 /var/log/plesk/panel.log | grep -i "letsencrypt\|ssl\|certbot"Troubleshooting: When Let's Encrypt Fails in Plesk
These are the most common failure scenarios and their fixes:
Error: "DNS challenge used another IP address"
This happens when your domain's DNS resolves to a different IP than your Plesk server. Common cause: the domain uses Cloudflare's proxy (orange cloud). Temporarily switch Cloudflare DNS to "DNS only" (grey cloud) during Let's Encrypt installation, then re-enable the proxy after the certificate installs.
Error: "Too many certificates issued"
Let's Encrypt limits certificate issuance to 50 certificates per domain per week and 5 failures per account per hour. If you've hit the limit (common when testing or after repeated failed installs), wait until the rate limit window resets (shown in the error message).
Auto-renewal fails for renamed certificates
Plesk's Let's Encrypt auto-renewal looks for a certificate named exactly "Lets Encrypt yourdomain.com". If you renamed the certificate in Plesk's certificate manager, auto-renewal will fail silently. Solution: delete the renamed certificate and reinstall via the Let's Encrypt extension — it will create a correctly named certificate.
Error: "Connection refused" or "Timeout" during validation
Let's Encrypt's validation crawler couldn't reach your domain on port 80. Check:
- Plesk's firewall (Tools & Settings > Firewall) — port 80 must be open
- CSF/iptables rules aren't blocking the Let's Encrypt IP ranges
- No
.htaccessrules redirect/.well-known/acme-challenge/requests to HTTPS before validation completes
SSL certificate works in browser but Plesk still shows "No SSL"
Try reassigning the certificate: go to SSL/TLS Certificates for the domain, select the Let's Encrypt certificate, and click "Install." Then clear Plesk's cache: plesk repair web -domain-name yourdomain.com.
Installing Let's Encrypt for Multiple Domains
If you manage many domains in Plesk, installing Let's Encrypt one-by-one is tedious. Use Plesk's CLI to batch-install certificates:
# Install for a single domain via CLI
plesk ext letsencrypt --issue -domain yourdomain.com -mail [email protected] -include-www 1
# Renew all certificates
plesk ext letsencrypt --renew-all
# List all Let's Encrypt certificates and their expiry dates
plesk ext letsencrypt --listFor bulk installation across all hosted domains, you can script this using Plesk's domain list:
plesk db -Ne "select name from domains where webspace_id=0 and hosting_type='vrt_hst'" | while read domain; do
plesk ext letsencrypt --issue -domain "$domain" -include-www 1
doneWildcard SSL Certificates With Let's Encrypt in Plesk
Standard Let's Encrypt in Plesk uses HTTP validation, which cannot issue wildcard certificates. For wildcard SSL (*.yourdomain.com), you need DNS validation. Plesk supports this through the SSL It! extension, which integrates with DNS providers like Cloudflare to automate DNS challenge responses for wildcard certificates.
To install SSL It!: go to Extensions > Extensions Catalog, search "SSL It!", install it, then configure your DNS provider API credentials. SSL It! handles both wildcard issuance and auto-renewal automatically.
FAQs
How often does Plesk auto-renew Let's Encrypt certificates?
Plesk's Let's Encrypt extension checks certificate expiry daily and renews any certificate that is within 30 days of expiring. Let's Encrypt certificates are valid for 90 days, so auto-renewal triggers around the 60-day mark. You can force immediate renewal via CLI: plesk ext letsencrypt --renew-all.
Can I use Let's Encrypt for all domains on my Plesk server?
Yes, but each domain's DNS must point to your server's IP, and port 80 must be accessible for HTTP validation. Let's Encrypt has rate limits: 50 certificates per registered domain per week. For servers hosting hundreds of domains, spread installations over time or use a staging environment to test.
Why does Let's Encrypt fail for domains behind Cloudflare?
When Cloudflare's proxy is enabled (orange cloud icon), the HTTP validation challenge from Let's Encrypt hits Cloudflare's edge servers, not your Plesk server — causing validation to fail. Switch the DNS record to "DNS only" (grey cloud) temporarily during certificate issuance. After the certificate installs, you can re-enable Cloudflare's proxy.
How do I install Let's Encrypt on a subdomain in Plesk?
Subdomains work the same as main domains: navigate to the subdomain in Plesk's domain list, go to Hosting & DNS > SSL/TLS Certificates, ensure SSL/TLS support is enabled in Hosting Settings, then click "Get it free" in the Let's Encrypt section. The subdomain must resolve to your server's IP before attempting installation.
My Let's Encrypt certificate expired even though auto-renewal was enabled. Why?
The most common causes: (1) The certificate was renamed after installation, breaking Plesk's auto-renewal lookup. (2) Port 80 was blocked by a firewall rule change. (3) The domain's DNS changed to a different IP. Check the Plesk panel log for the specific error: tail -n 200 /var/log/plesk/panel.log | grep letsencrypt.