Troubleshooting SSL/TLS Certificate Errors
SSL/TLS errors prevent secure connections and scare away visitors. Learn to diagnose and fix the most common certificate problems.
Key Takeaways
- The certificate has expired or the device clock is wrong.
- The certificate doesn't match the domain name.
- The certificate was signed by an untrusted authority.
- An HTTPS page loads resources (images, scripts) over HTTP.
- Let's Encrypt certificates expire every 90 days and must be auto-renewed.
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ERR_CERT_DATE_INVALID
Cause
The certificate has expired or the device clock is wrong.
Solution
Check your device's date and time settings. If correct, the website needs to renew its certificate. Let's Encrypt certificates expire every 90 days and must be auto-renewed.
ERR_CERT_COMMON_NAME_INVALID
Cause
The certificate doesn't match the domain name. A certificate for example.com won't work on www.example.com unless it includes both or uses a wildcard.
Solution
Obtain a certificate that covers all required domain names. Use Subject Alternative Name (SAN) entries for multiple domains or wildcard certificates for subdomains.
ERR_CERT_AUTHORITY_INVALID
Cause
The certificate was signed by an untrusted authority. Self-signed certificates, expired intermediate certificates, or unknown CAs trigger this error.
Solution
Ensure the full certificate chain is installed on the server. Include intermediate certificates in the correct order.
Mixed Content Warnings
Cause
An HTTPS page loads resources (images, scripts) over HTTP.
Solution
Update all resource URLs to use HTTPS or protocol-relative URLs. Check for hardcoded HTTP URLs in CSS, JavaScript, and inline HTML.
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Troubleshooting SSL/TLS Certificate Errors
SSL/TLS certificate errors prevent secure connections and scare away visitors. This guide explains common certificate warnings, their causes, and step-by-step fixes for website operators and visitors.