When opening Server Manager on the server, in the notifications you will see an error stating Refresh Failed.

At this stage, you will not be able to add any features to the server and you will not be able to add or remove windows features.

A pop-up about collecting inventory data and a refresh error saying “Configuration refresh failed with the following error: Invalid class” will show.

Before proceeding you can take a backup of this by using the command below
winmgmt /backup %computername%_MM_DD_YEAR.WMI_backup

To fix the problem you would need to do the following in a command prompt as Administrator.

winmgmt /verifyrepository
winmgmt /salvagerepository
winmgmt /resetrepository

This will resolve the problem and when you relaunch the Server Manager, you will be able to add the features with no issues.