To troubleshoot the issue please do the following:
- Go to Core console and click on Replication icon
- Expand all incoming replication links and verify if machine name is present there
- If it's there, select it and remove from the replication
- Retry adding the agent to protection.
If there are no incoming replication links or machine is not shown under incoming Cores' replication, then direct registry modification will be required.
- Stop the Core service
- Open regedit on the Core server
- Navigate to HKLM\Software\Apprecovery\Core\Agents
- Selecting subkey GUIDs one by one, find which one is correlating to agent
- Once found, back that GUID to the REG file and delete it
- It's also recommended to expand HKLM\Software\Apprecovery\Core\Replication\RemoteCores\Masters and Slaves and make sure that GUID entries there are matching actual replications. NOTE: Masters are for incoming replications. Slaves for outgoing.
- If there's a bogus entry (exists in registry but not in GUI), then back it up to the REG file and delete it
- Re-start the Core service and retry adding the agent to protection.
If the Core still fails to add the agent to protection with the same error, try the following:
- Go to the agent machine.
- Stop the agent service.
- Locate the following registry key branch "HKEY_LOCAL_MACHINE\SOFTWARE\AppRecovery\Agent\AgentId"
- Delete the "AgentId" registry key.
- Restart the agent service.
The core should be able to add the agent to protection.