# Common Browser Errors

When using internal certificates, browsers are very strict. Here are common error codes and what they mean.

## NET::ERR_CERT_AUTHORITY_INVALID hiding

**Cause:**
The browser does not recognize the Root CA that issued the certificate.

**Solution:**
You have not installed the TrustLab Root CA on your device.
-> [Go to Installation Guide](/guide/getting-started/install-root-ca)

## NET::ERR_CERT_COMMON_NAME_INVALID

**Cause:**
The domain name you are visiting (e.g., `app.local`) does not match the names listed in the certificate.

**Solution:**
Check the **SANs (Subject Alternative Names)** of the certificate.
1. Click the "Not Secure" icon in the address bar.
2. View Certificate.
3. Check "DNS Names". If the domain is missing, you must **Re-issue** the certificate.

## NET::ERR_CERT_DATE_INVALID

**Cause:**
The certificate has expired or the system clock is wrong.

**Solution:**
1. Check your computer's date and time.
2. If time is correct, the certificate is expired. [Renew the certificate](/guide/certificates/renewal).