How does an SSL certificate chain bundle work?

Question

I\'ve created a chain hierarchy like this.

root-ca ==> signing-ca ==> subordinate-ca ==> server

It is mentioned to create chain bu

Answer 1

The original order is in fact backwards. Certs should be followed by the issuing cert until the last cert is issued by a known root per IETF's RFC 5246 Section 7.4.2

This is a sequence (chain) of certificates. The sender's certificate MUST come first in the list. Each following certificate MUST directly certify the one preceding it.

See also SSL: error:0B080074:x509 certificate routines:X509_check_private_key:key values mismatch for troubleshooting techniques.

But I still don't know why they wrote the spec so that the order matters.