Private certificate issue with chef server (knife ssl check - unable to get local issuer certificate)

I’m using open source chef12 server and I have created a private certificate for chef-server rather using self signed certificate. As i got error while using private certificate as below for “knife ssl check”:

WARNING: There are invalid certificates in your trusted_certs_dir. OpenSSL will not use the following certificates when verifying SSL connections:

c:/Users/test/.chef/trusted_certs/ unable to get local issuer certificate

I followed steps given in “” for private certificate adding server.crt and root.crt and configured the nginx server. But when i tried “knife ssl fetch” it downloaded server.crt and root.crt seperately in trusted_certs folder and getting the same error for “knife ssl check” again.

Please help me how to configure chef-server with private cert without error.