What is an 'SSL handshake error empty server certificate chain' and what does it signify?

An 'SSL handshake error empty server certificate chain' signifies that during the SSL/TLS handshake process, the server presented its primary (leaf) certificate, but failed to send the necessary intermediate certificate(s) that link the leaf certificate back to a trusted Root Certificate Authority (CA). Clients, such as web browsers, receive the leaf certificate but cannot validate its authenticity because they don't have the full chain of trust. This results in the client terminating the connection, typically displaying a 'certificate not trusted' or 'SSL handshake failed' error, even if the primary certificate itself is valid and not expired.