One of my ConfigMgr community friend Harjit Dhaliwal experienced this issue while doing SCCM 2012 SP1 to R2 client upgrade. All credits to him for doing research and coming up with these finding!! I thought of sharing this because this would be a help for some others in the community. Also, be aware of the SCCM 2012 R2 upgrade checklist available SCCM 2012 SP1 to R2 Upgrade Checklist.
End users systems were getting rebooted after ConfigMgr 2012 R2 client upgrade. This could be avoided using proper maintenance window, especially the new maintenance window option in SCCM 2012 R2 dedicated for software updates (more details http://technet.microsoft.com/en-us/library/dn236351.aspx#BKMK_WhatsNew_Software ). This unexpected reboot may happen only in the scenario which is explained below :-
What Triggered the forced reboot ?
Security Update for Microsoft Visual C++ 2010 Service Pack 1 Redistributable Package (KB2565063). A security issue has been identified leading to MFC application vulnerability in DLL planting due to MFC not specifying the full path to system/localization DLLs. You can protect your computer by installing this update from Microsoft. After you install this item, you may have to restart your computer.
How security patch installation got triggered suddenly after ConfigMgr SCCM R2 client upgrade ?
Since, “Security Update for Microsoft Visual C++ 2010 Service Pack 1 Redistributable Package (KB2565063)” was released/revised in March 2012 and the update is in a Software Update Group which is deployed in April 2012, the update has become mandatory and passed due for the systems that now need it due to the NEW CM 2012 R2 client prerequisite, and therefore the reboot requirement which some of our CM users have noticed.
Few more details on NEW CM 2012 R2 client prerequisite
Microsoft Visual C++ 2010 Redist (version 10.0.40219.1) is now a prerequisite for the ConfigMgr 2012 R2 client (5.00.7958.1000) install, along with Microsoft Visual C++ 2005 Redist (8.0.6100).
You’ll find references to it in the ccmsetup.xml file located in c:\windows\ccmsetup. Also, on the ComfigMgr server, you’ll find the prereq installers located in c:\Program Files\Microsoft Configuration Manager\Client\x64 or \x86 and the vcredist_x64.exe or vcredist_x86.exe is the 2010 redist.
The client prereq info located in the doc below is incorrect.
When you look at client prerequisites, it’s very clearly mentioned that .Net Framework 4.0 installation can trigger a reboot (When the .NET Framework 4 is installed on computers, a restart might be required to complete the installation) but this scenario is not explained over there.