What Is a Certificate Chain?
A certificate chain (or chain of trust) is a sequence of certificates linking your server's SSL certificate to a trusted root Certificate Authority (CA). Each certificate in the chain is signed by the next, creating a verifiable path from your domain's certificate to a root CA that browsers inherently trust.
How It Works
Your SSL certificate is signed by an intermediate CA, which is signed by another intermediate or the root CA. Browsers verify each link in the chain. If any certificate is missing, expired, or revoked, the chain breaks and the browser shows a security warning.
Why It Matters
An incomplete certificate chain is one of the most common SSL errors. If your server doesn't send the intermediate certificates, some browsers and clients will fail to establish a secure connection, even if your certificate itself is valid.
Common Issues
- Missing intermediate certificates on the server
- Incorrect certificate order in the chain
- Expired intermediate certificates
- Cross-signed certificates causing confusion