When you try to install a schema update for a newer Exchange Server environment , the process will fail with the error "A reboot from a previous installation is pending. Please restart the system and then rerun Setup.". Unfortunately, the hostname of the system in question is not named. This error occurs even if you have checked and rebooted all your Exchange 2013 servers.
Before a Schema update to Exchange Server 2016 will take place, the domain controllers will check if all prerequirements for the installation is fullfilled on every Exchange server and the responsable Windows 2012 servers. Sometimes the domain controllers will get a wrong result for Exchange 2013 servers, that one ore more servers will have a outstanding reboot session process. After you have reboot any Exchange 2013 servers, you will get the same error as well.
"A reboot from a previous installation is pending. Please restart the system and then rerun Setup."
The reason is, that one or more involved Windows 2012R2 or Windows 2012 servers, that are hosting Exchange 2013 servers, have an information in it's registry, that there is change request for one ore more file names after a reboot. The registry key is the following:
First please check every Exchange Server if any update is responding a needed reboot of the server and reboot this Exchange server. If the error repeat after rebooting every Exchange 2013 sevrer, the problem could be resolved by deleting a specified registry key on every involved Exchange 2013 server:
1. Open the regedit tool 2. Browse to the following registry folder HKLM\SYSTEM\CurrentControlSet\Control\SessionManager 3. Check if the registry key "PendingFileRenameOperations" is existing 4. If existing, right click the registry key "PendingFileRenameOperations" in the right pane and choose "Delete" 5. Repeat this tasks on all Exchange 2013 servers in your environment 6. Restart the schema update