Fixing SSL Certificate Issues (Let’s Encrypt, HTTPS Setup)

Common SSL Errors

• Certificate expired.
• Mixed content warnings (HTTP resources on HTTPS pages).
• Domain mismatch (certificate doesn’t cover subdomains).

How to Fix:

1. Renew Let’s Encrypt Certificate

sudo certbot renew --dry-run  # Test renewal
sudo certbot renew            # Actual renewal
    

2. Fix Mixed Content Warnings

Update all URLs to HTTPS in your code:

<!-- Before -->
<img src="http://example.com/image.jpg">

<!-- After -->
<img src="https://example.com/image.jpg">

3. Redirect HTTP to HTTPS

Add to .htaccess (Apache):

RewriteEngine On
RewriteCond %{HTTPS} off
RewriteRule ^(.*)$ https://%{HTTP_HOST}%{REQUEST_URI} [L,R=301]
    

4. Verify Domain Coverage

Use a wildcard certificate for subdomains:

sudo certbot certonly --manual --preferred-challenges=dns -d *.example.com
    

Prevention Tips

• Set up auto-renewal for Let’s Encrypt certificates.
• Use SSL Labs Tester to audit your setup.
• Enforce HTTPS in your CMS (e.g., WordPress settings).