A website certificate does not stand alone. It is linked through one or more intermediate certificates back to a root that browsers trust.
The website's own certificate is signed by an intermediate certificate, which is signed by a root certificate. Browsers hold the roots, not the intermediates. Only the roots do not need to be sent along.
The server has to deliver its own certificate and the intermediates. If an intermediate is left out, the browser cannot complete the chain.
Some browsers remember or fetch missing intermediates and show no error, while other devices, tools and mail servers fail. That makes the problem hard to spot.
A chain check tool lists every certificate the server sends and shows which link is missing. The certificate details in a browser also show the path.
SSL Domain Detective lists the certificates of your domains and when each one ends. Open SSL Domain Detective
SSL Domain Detective is now available on the App Store.
Last reviewed: 2026-11-02
#SSL #TLS #Certificates #DomainExpiry #SysAdmin #MSP #iOS
This page gives general information and is not legal, financial or medical advice. [email protected]