ERR_CERT_COMMON_NAME_INVALID — What It Means & How to Fix It

What Does This Error Mean?

ERR_CERT_COMMON_NAME_INVALID means the SSL certificate the website provided does not match the domain name you are visiting. Every SSL certificate is issued for a specific domain name. If the certificate says 'example.com' but you are visiting 'www.example.com' — or a completely different site — your browser will block the connection. This is a security feature to prevent fake websites from impersonating legitimate ones.

Affected Models

Google Chrome
Microsoft Edge
Firefox
Safari
All modern browsers
Windows
macOS
Android
iOS

Common Causes

The website's SSL certificate was not issued to include all required domain name variations (e.g., with and without 'www')
You are being redirected through a proxy or network device that serves its own certificate
The website recently moved to a new domain but the old certificate is still being served
Your hosts file has been modified to point a domain to the wrong server
Malware or a man-in-the-middle attack is intercepting your connection

How to Fix It

Click on the 'Not secure' warning or the certificate error in your browser to see what domain the certificate is actually issued for. Compare it to the URL you are visiting.

This helps you understand whether it is a website issue or a network interference issue.
Try accessing the site with and without 'www' in the URL. For example, try both 'example.com' and 'www.example.com'. One version may have a valid certificate.

Some sites have certificates that only cover one version of the domain.
If you are on a public Wi-Fi network (coffee shop, hotel, airport), disconnect and switch to your phone's mobile hotspot. Public networks often intercept HTTPS connections.

This is a significant security risk. Never enter passwords on public Wi-Fi when you see certificate errors.
Flush your DNS cache and clear your browser cache. On Windows, open Command Prompt and type: ipconfig /flushdns. In Chrome, press Ctrl+Shift+Delete and clear all cached data.

Cached DNS entries might be pointing you to the wrong server.
Run a malware scan using Windows Defender or Malwarebytes. Some malware modifies your hosts file or network settings to redirect your traffic to fake servers.

A clean malware scan gives you confidence that your network is not being hijacked.

When to Call a Professional

If this error appears on your own website, your SSL certificate needs to be corrected or reissued by your hosting provider. If you suspect a man-in-the-middle attack (especially on a public Wi-Fi network), disconnect immediately and avoid entering any passwords until you are on a trusted network.

Frequently Asked Questions

Is it safe to click 'Proceed anyway' when this error appears?

It depends on the situation. If you are on a corporate or school network where IT uses a proxy with a custom certificate, it may be safe. However, if you are on a public network or visiting a sensitive site, do not proceed. A certificate mismatch can indicate your connection is being intercepted.

Does this mean the website is fake or a scam?

Not necessarily, but it is a red flag. The most common reason is a legitimate site with an incorrectly configured SSL certificate. But in rarer cases, it can indicate a phishing site using an impersonated domain or a man-in-the-middle attack. If in doubt, do not enter any personal information.

Can my company's network cause this error?

Yes, very commonly. Many companies use network security appliances that inspect all HTTPS traffic. To do this, they install their own certificate on company devices and use it to decrypt and re-encrypt your traffic. If the proxy's certificate does not match the site you are visiting, this error appears. This is normal on corporate networks — ask your IT department.