SOAP Adapter – Confusing error with an untrusted Root Certificate Authority

I recently wrote about problems with two-factor authentication and installing a certificate in the correct certificate store. Well, we’ve had similar problems, this time securing the transport link on a SOAP adapter, which resulted in the following error:

Could not establish trust relationship for the SSL/TLS secure channel with authority ‘your machine name’. The underlying connection was closed: Could not establish trust relationship for the SSL/TLS secure channel.

After some digging, it turns out that the problem is due to an untrusted certificate issuer (Certificate Authority) for the cert we were trying to use. Adding the root certificate to the list of Trusted Root Certification Authorities resolved the issue.