The warning you're seeing:
“Application 'C:\Program Files\Microsoft Office\root\Office16\EXCEL.EXE' (pid 29740) cannot be restarted - Application SID does not match Conductor SID.” is related to Windows Restart Manager and typically occurs in Remote Desktop Services (RDS) environments. It happens when an application, like Excel, tries to restart but fails due to a mismatch in security identifiers (SIDs) between the running application and the expected session.
The Restart Manager attempted to restart Excel, possibly after an update or when reconnecting a session.
The security context (SID) of the running Excel process doesn't match the expected SID (the "Conductor SID").
This usually happens when the application is running under a different user session or account than expected.
What you can do is You can ignore this warning if no one is experiencing issues. Make sure Office is fully updated on the RDS server. Ensure Office apps are not being launched with elevated permissions or under different user contexts.
If Excel not restarting becomes a problem, you can consider disabling the Restart Manager for Office apps through Group Policy or local settings, although this is rarely necessary.
Hope this helps