After upgrading to 8.x, the Configuration Wizard may crash when updating/adding trustees. An error similar to the following may be shown:
Crash while upgrading from 7.5 to .0 If a user is explicitly added as a trustee, and that user is no longer in Active Directory, the server manager wizard crashes on updating/adding trustees. It fails because when it performs get-aduser using the SID the return is nul and it causes the wizard to crash.
This issue will be resolved in version 8.0, update 7.