Updated August 24, 2016
The following error occurs after a security scan:
This server's certificate chain is incomplete. Grade capped to B.
All Serv-U versions
Any of the following triggers the error:
Go back to your Certificate vendor and ask them to give you the necessary intermediate certificates, after which you will need to add them to your configuration.
It will display in the "Additional Certificates (if supplied)" section, and the chain issue will go away (if it's installed correctly).
You should not include the Root certificate.