Checking & Troubleshooting

How to check SSL certificates, diagnose errors, fix common problems, and verify configurations.

When something goes wrong with an SSL certificate, browsers show scary warnings that drive visitors away. These articles cover how to check certificates using browsers, command-line tools, and online checkers, plus how to diagnose and fix common errors.

For a comprehensive overview, see our SSL Troubleshooting Guide.

How to Check an SSL Certificate

Four ways to check any website's SSL certificate: browser inspection, online tools, command line, and monitoring. Plus a comparison of free SSL checker tools.

How to Check SSL Certificate Expiration Date

Five ways to check when an SSL certificate expires: browser, OpenSSL, online tools, cURL, and monitoring platforms. Never be surprised by an expired cert.

How to Check SSL Certificates in Your Browser

Step-by-step guide to viewing SSL certificate details in every major browser. Check expiry dates, certificate chain, and issuer without leaving your browser.

How to Check SSL Certificates with OpenSSL

OpenSSL commands for checking SSL certificates: view expiry dates, decode certificates, verify chains, and test TLS connections. Copy-paste commands included.

How to Decode an SSL Certificate

Decode SSL certificates in PEM, DER, and PKCS formats. Read certificate fields, extract SANs, check key usage, and understand the certificate structure.

How to Validate an SSL Certificate

Validate SSL certificates are correctly installed and trusted. Check chain completeness, hostname matching, protocol support, and certificate transparency.

How to Fix SSL Certificate Errors

Troubleshoot common SSL certificate errors: expired certificates, name mismatches, untrusted issuers, mixed content, and chain issues. Step-by-step fixes.

Invalid SSL Certificate: What It Means and How to Fix It

Every reason an SSL certificate can be invalid: expired, wrong domain, self-signed, revoked, incomplete chain. Browser error messages explained and step-by-step fixes.

SSL Certificate Error Code 526: Causes and Fixes

Cloudflare error 526 means the origin SSL certificate is invalid. Learn what causes it, how to diagnose it, and how to fix it step by step.

What Happens When an SSL Certificate Expires

The full timeline of an SSL certificate expiration: browser warnings, broken APIs, SEO impact, and lost revenue. What breaks and how fast.

Famous SSL Certificate Expiry Disasters

Real-world SSL certificate expiry incidents at Microsoft, Spotify, LinkedIn, and more. What happened, what it cost, and how monitoring would have prevented it.