Article ID: 2679682
When you remove a library server from System Center 2012 Virtual Machine Manager and then immediately add it back as a library server, you may receive the following error:
The agent removal process is still in the process of creating a failure for the new install job.
To resolve this issue, wait a few seconds and then retry the installation again. If it continues to fail, reboot to the library server to stop any agent process that may be preventing the installation, then try the installation again.
(http://go.microsoft.com/fwlink/?LinkId=151500)for other considerations.