On a System Center Data Protection Manager (DPM) 2007 agent, you receive the following error messages about communication issues:
A DPM agent failed to communicate with the DPM service on <server> because of a communication error. Make sure that <server> is remotely accessible from the computer running the DPM agent. If a firewall is enabled on <server>, make sure that it is not blocking requests from the computer running the DPM agent (Error code: 0x800706ba, full name: <server>).
DPM failed to communicate with the protection agent on <server> because access is denied. (ID 42 Details: Access is denied (0x80070005))
Error 270: The agent operation failed on <server> because DPM could not communicate with the DPM protection agent. The computer may be protected by another DPM server, or the protection agent may have been uninstalled on the protected computer.
This problem occurs if a DPM 2007 machine account is missing from one of the following security groups on the protected server:
Distributed COM Users
If the DPM 2007 machine account is missing from any of the security groups that are listed in the "Cause" section, manually add the DPM machine account.
For example, if the DPM server's name is DPM01, and if this name belongs to the Contoso domain, you should see "Conotoso\DPM01" as a member of each group on the protected server.
In a situation where the protected server is a domain controller, a failed installation of the protection agent could result in the removal of the DPMRADmTrustedMachines and DPMRADCOMTrustedMachines groups. By upgrading to DPM 2007 Service Pack 1 (SP1), you will resolve this problem. Or, you can resolve this problem by running the following command:
<drive letter>:\Program Files\Microsoft Data Protection Manager\bin\ SetDpmServer.exe -dpmServerName <DPM 2007 server name>
For example, the last part of this command might resemble the following:
SetDpmServer.exe –dpmServerName DPM01
"DPM01" is the actual DPM server name.
This command will re-create the two groups in Active Directory, and it will add the DPM 2007 machine account to these groups and to the Distributed COM domain users group.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.