I've just upgraded my core server from Management Suite 8.7 SP5 to Management Suite 8.8 SP3 and rebuilt the Agent Configurations. When I upgraded some test system with the new Agent Configurations, the inventory scanner gives the above error message. The really odd thing is that it seems that sometimes it works because the core is intermittently getting new scans from these test systems, but manually running the inventory scanner produces the error message. I wasn't able to telnet to the core server on port 5007, but I'm not sure it it's because we have a management gateway that these devices need to connect through. There doesn't seem to be a problem with the services on the core, as scans are still coming back from the non updated agent devices. Also, these devices all have the client certs present and are able to update the virus definitions via the core server.
Any ideas would be appreciated.