Azure directory synchronisation fails, and in the Application event log on the system running Azure directory synchronisation, an “Invalid namespace” message is registered.
In the “Directory Integration” section of Azure AD, the “Last sync” date is older than the last scheduled sync time. Additionally, an “Invalid namespace” message is registered in the Application event log on the system running Azure directory synchronisation software and the “Synchronization Service Manager” software (miisclient.exe) shows that the tasks are no longer running as per the history.
This is caused by the de-registration of the “MicrosoftIdentityIntegrationServer” WMI namespace.
Re-register the WMI namespace by locating the mmswmi.mof file and executing the following command: –