Hi Linjo,
Thanks for the response. It isn't a security server I'm upgrading but I guess the same might apply if it is using SSL. The certificates in question are all internally generated so the host server should have the CA root cert in place, but I've copied the 'vdm' specific certificate into that same root store. I'll process an upgrade again later today/tomorrow and let you know how I get on.
Cheers
John