The CW Corner – Let’s Encrypt Rate Limits Explained: 5 Steps to Avoid SSL Certificate Headaches

by Charles Oropallo | Oct 18, 2025 | Do-It-Yourself

If you secure many sites with free Let’s Encrypt SSL, you may hit a wall. Suddenly, certificate requests stop cold. One day everything works. The next, you see rate-limit errors and wonder what happened.

Here’s the thing. Let’s Encrypt secures over 350 million websites with free SSL. To keep things stable and safe, they enforce strict rate limits. These limits can surprise even seasoned developers. They bite hardest when securing many domains or subdomains at once.

Understanding these limits prevents headaches. It also keeps your sites secure and your business running. I’ll explain what the limits mean. I’ll share five practical steps to avoid SSL issues before they happen.

What Are Let’s Encrypt Rate Limits?

Think of Let’s Encrypt rate limits like a busy restaurant. It can serve only so many guests each hour. They are not there to hassle you. They ensure fair access and protect the system.

The key limit is 50 certificates per registered domain every 7 days. “Registered domain” means your eTLD+1, or main domain. If you own example.com, all subdomains share that weekly pool. That includes www, blog, and shop subdomains.

That’s not the only limit. You get 5 failed validation attempts per domain per hour. Repeated failures trigger a temporary lockout. Common causes include DNS or firewall issues. There’s also a duplicate certificate limit of 5 per week. Renewals do not count against the 50-certificate quota.

Account creation is limited too: 10 accounts per IP every 3 hours. This prevents abuse through mass accounts. It can also affect legitimate teams that need several accounts.

Step 1: Use Wildcard Certificates for Multiple Subdomains

Here’s your first defense against rate limits. Use a single wildcard certificate, not many subdomain certificates. One wildcard covers all subdomains under your domain.

A wildcard for *.example.com secures www, blog, shop, and new subdomains. You issue only one certificate. This slashes issuance volume and stays within Let’s Encrypt limits.

Even better, a single certificate can list up to 100 domains. Managing many brands? Combine domains into fewer certificates. One cert can cover yourcompany.com, .net, and .org.

Look at your setup. Are you requesting one certificate per subdomain? If so, you burn limits quickly. Switching to wildcard certificates is often the top fix.

Step 2: Test in the Staging Environment First

Before deploying live, test in Let’s Encrypt’s staging environment. It’s a safe practice kitchen. Mistakes don’t affect customers.

Staging has relaxed limits: 50 new registrations per IP per 3 hours. Production allows only 10. Use staging to test SSL, fix DNS, and refine deployment.

Many teams skip this step in a rush to go live. That’s when rate-limit problems strike. You issue, it fails, you retry, and hit five failures. Now you must wait.

Follow this rule. Do not issue a production certificate until staging succeeds. Spend 15 extra minutes. It could save days later.

Step 3: Implement Protective Safeguards

Smart hosting platforms add safeguards to prevent runaway certificate requests. You should do the same.

Many platforms lock SSL provisioning after three failures. They stop before Let’s Encrypt’s limit of five. That buffer prevents retry loops and protects weekly limits.

If you manage SSL yourself, add similar safeguards. Monitor requests per domain and per week. Create alerts near the limits. Add automatic delays between retries.

Do not rely on manual steps. SSL issues feel urgent, and pressure creates mistakes. Automation removes human error in Let’s Encrypt rate-limit management.

Step 4: Monitor and Space Out Certificate Requests

If you manage many sites or a SaaS, timing matters. Be strategic with certificate requests. Avoid securing everything at once.

Let’s Encrypt allows 10 certificates per IP every three hours. Migrating dozens at once? Pace your requests. Spread them over days, not one afternoon.

Keep detailed logs of issuance times and domains. This is essential for weekly limits. Know exact counts for each domain over seven days before requesting more.

Use a spreadsheet or database to track issuance dates, renewals, and limit usage. Seeing requests visually helps avoid accidental Let’s Encrypt limit hits.

Step 5: Fix Root Causes Before Retrying Failed Requests

This might be the most important step. When provisioning fails, do not retry immediately. The seven-day window also tracks failed attempts per domain.

Instead, find and fix the root cause. Common causes include DNS mistakes, blocked HTTP validation, or domain verification issues. Retrying without fixes only wastes your limits.

Some common issues to check when certificates fail:

• DNS records pointing to the correct IP address
• Firewall rules allowing HTTP validation on port 80
• Web server configuration properly handling validation requests
• Domain ownership verification working correctly

Follow this rule of thumb. Wait at least an hour between failures. Do not retry until you fix the specific problem. Many providers recommend this. It prevents accidental lockouts.

What Happens When You Hit Rate Limits

Despite your best efforts, you may still hit limits. When it happens, wait for the window to reset. The main certificate limit resets after seven days.

While you wait, consider alternatives. Issue wildcard certificates where missing. Consolidate domains into fewer certificates. For critical needs, consider a commercial CA as a temporary last resort.

Most important, learn from the incident. Review what happened. Update processes to prevent repeats. Confirm your safeguards work properly.

Remember, Let’s Encrypt rate limits keep the service stable for everyone. Follow the five steps. Use wildcards. Test in staging. Add safeguards. Monitor usage. Fix root causes early.

The key is proactive planning, not reactive troubleshooting. With preparation, you can keep sites secure without hitting these limits.