Mail Agent fails to start with "Error 4708 An instance of the agent already exists in the memory." (4281143)

When trying to synchronize mailboxes from source to target, the following error is found in the agent log:

"CBaseApp::Init Error     4708     An instance of the agent already exists in the memory. The second instance of the same agent cannot be started."

Stopping the Mail Agent and restarting it does not resolve the problem.

The emwmsa.exe or emwmta.exe process still exists on the Agent Host Server even after stopping the agent.   When starting the agent again, it detects that an instance of the agent already exists in memory.

RESOLUTION 1

1. Stop all instances of the Mail Agent on the Agent Host.

2. Log on to the Agent Host and open Task Manager.

3. End the emwmsa.exe or emwmta.exe process if it is still running.

4. Start the Mail Agent again from the QMM Console

5. Monitor the agent and see if the error still happens.

RESOLUTION 2

Rebooting the agent host should clear the issue.

RESOLUTION 3

If this error is occurring frequently, then you may be able to resolve the issue permanently by removing and reinstalling both Shared Components and the Mail Source or Target Agent from the QMM Console. Having done this you should then reapply the agent configuration. From the Mailbox Synchronization Job node  | Right mouse click on the server pair  | Select "Reapply Agent Configuration".