The Management Server task that remotely installs the agent was interrupted.
This can happen when:
The HealthService is being shut down while a remote agent installation is already in progress.
The Data Access service was being restarted while submission of the task was happening.
Ensure the Health Service and Data Access service are up and running. Also check the Operations Manager event on the Management Server your User Interface was connected to and check for any errors with the Health Service or Data Access service.