I kept having errors adding hosts to a VMM server, even though all of the prereqs were met.
I received the following errors every time I tried to add the hosts:
Agent installation failed copying C:\Program Files\Microsoft System Center 2012\Virtual Machine Manager\agents\I386\3.1.6011.0\msiInstaller.exe to \\<hostname>\ADMIN$\msiInstaller.exe.
The specified network name is no longer available
1. Ensure <Hostname.FQDN> is online and not blocked by a firewall.
2. Ensure that file and printer sharing is enabled on <Hostname.FQDN> and it not blocked by a firewall.
3. Ensure that there is sufficient free space on the system volume.
4. Verify that the ADMIN$ share on <Hostname.FQDN>exists. If the ADMIN$ share does not exist, reboot <Hostname.FQDN> and then try the operation again.
The VMM management server was unable to impersonate the supplied credentials.
To add a host in a disjointed domain namespace, ensure that the credentials are valid and of a domain account. In addition, the SCVMMService must run as the local system account or a domain account with sufficient privileges to be able to impersonate other users.
This took me much longer than the 5 minutes it should have taken to figure out.
Basically, we have two links to the remote hosts. Traffic to that remote site is routed differently depending on the which subnet it is on. Also, we have a VLAN that is specifically set for switch management. Once I moved the VMM server to a VLAN that was NOT restricted, the hosts added just fine.
If that isn’t your issue, but you get the Error (415) above, there is a knowledge base article that says you may have to enable the fileserver role first on a 2012 host.