The purpose of this wiki page is to provide the steps on how to re-register, or register the FIM WMI Provider.
Following symptoms might occur:
I got once the following setup error:
"Error 25050. The Forefront Identity Manager Synchronization Service setup wizard cannot set Windows Management Instrumentation (WMI) permissions. Ensure you have the correct permissions for this operation, and then try running this wizard again. To run WMI remotely, you must manually set the remote enable permission. Invalid namespace."
When looking at WMI namespaces, /root/MicrosoftIdentityIntegrationServer was missing.
I fixed the situation by uninstall/reinstall FIM Synchronization Service ("MSI change" did not help), but this will hopefully repair the namespace without reinstalling.
Hope it helps others :)