I've run into this after updating to Mac OS 10.12 and then updating to Sophos SafeGuard Enterprise client 8.00.1. I keep getting this error even after adding the certificate into the System Keychain. I've also attempted to browse to the address in the error message "https://<internal server fqdn>/SGNSRV/trans.asmx" and checked to made sure to trust it manually through Safari. I read other posts on the forum and made sure it was removed from the "login" Keychain but made sure it is in "System" and is trusted.
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