How to Fix SSL Certificate Errors (NET::ERR_CERT_INVALID)

Fixing SSL Certificate Errors

SSL errors show a "Your connection is not private" warning in browsers, which drives visitors away. Here is how to diagnose and fix them.

Common SSL Error Messages

Fix 1 — Renew an Expired Certificate

Let's Encrypt certificates expire every 90 days but auto-renew. If auto-renewal failed:

1. Log into cPanel → Security → SSL/TLS Status
2. Find your domain and check the expiry date
3. Click Run AutoSSL to force renewal
4. Wait 5 minutes and refresh your site

Fix 2 — Certificate Domain Mismatch

If your certificate is for yourdomain.co.ke but visitors access www.yourdomain.co.ke:

1. cPanel → SSL/TLS Status
2. Ensure both yourdomain.co.ke AND www.yourdomain.co.ke are listed
3. Run AutoSSL to cover both

Fix 3 — Mixed Content (HTTP resources on HTTPS page)

Your page loads over HTTPS but includes HTTP images, scripts, or stylesheets.

For WordPress:

1. Install Really Simple SSL plugin
2. It automatically fixes mixed content issues

Manually — find HTTP resources:

1. Open Chrome DevTools (F12) → Console
2. Look for "Mixed Content" warnings
3. Update the URLs in your HTML/CSS to use https://

Fix 4 — Force HTTPS in WordPress

1. WordPress admin → Settings → General
2. Change both URLs from http:// to https://
3. Save changes

Fix 5 — Clear SSL State in Browser

Windows: Internet Options → Content → Clear SSL State

Or simply clear browser cache and cookies.