After updating the VMM Server, the administrator has an additional task to perform which is the VMM agent update on all hosts managed by the VMM.
The process is simple, after the VMM Server upgrade the administrator may notice that the Host Status is showing up as Needs Attention, as shown in the image below.
In order to identify if that warning is really related to the agent upgrade, right-click on the desired host and click Properties. In the new window, click on Status. In the current example, we could identify that the issue is related to the agent version as depicted on the image below.
After identifying the reason of the warning, right-click on the server and then Update Agent.
In the new window, select an account that has necessary permissions to install an agent update on the host from the Run As account list, or type in a credential with enough permissions and click OK.
The administrator can track the process using the Jobs area.
After completion the server should be back to normal on the VMM Console.