Importing OVA into VCSA 6.5 fails – The operation failed for an unknown reason

To resolve this issue follow the below steps

1. Open the IP of the vcenter in IE/Chrome
2. Download Certificates by clicking on “Download trusted root CA certificates“
3. Follow the steps to import the certificates in the following hyper link  https://technet.microsoft.com/en-us/library/cc754841.aspx