On Windows, OpenFin uses the Certificate Store to validate certificates. Issues may arise if the certificate is not installed in Trusted Root Certificates on the local machine or the certificate's CN (Common Name) is not matching with the domain you are accessing.
In order to install the certificate on trusted roots,
Click on the red alert icon on the top left of the address bar, form drop down menu select certificate.
Then navigate to the detail tab on the certificate window, from bottom right click on Copy to File, Export the certificate in
DERencoding set the name of the certificate and Finish.
certmgr.mscexpend the Trusted Root Certificate Authorities tree.
Right click on Certificate from the drop down select all task then click import select your certificate chose
Place all certificates in the following storeand proceed to finish.
If this doesn't solve your problem, there is an issue in the certificate or someone trying to gets in the middle (Man in the Middle Attack)! concern your system administrator.