In my previous post, I showed how to enable the upgrade to Windows Server 2012 Core from an application point of view (the application being the Active Directory).
To continue my story, you need to know that my Hyper-V server is still running Windows Server 2008 R2 (of course I could upgrade my host first, but hey, we want to learn something, don't we?)
Not immediately it is obvious that if you intend to keep your host on this release, you are going to face some issues.
A first problem - which you may or may not encounter depending on how you update your servers - is described in the following KB Article: "You cannot run a Windows 8-based or Windows Server 2012-based virtual machine in Windows Server 2008 R2". This article explains that there is an issue occurs because the Hypervisor does not handle the one-shot synthetic timer correctly. This can cause the virtual machine to stop responding and/or cause you to receive stop error messages which makes the computer and all running VMs to stop (which sounds to me like a blue screen). A patch that you run on your Hyper-V server can be obtained here or by going to the article mentioned above.
The second problem you most definitely will encounter, and which you could already see in my previous post, is the following:
The compatibility report shows that there is a device that might not work properly (the Microsoft Emulated S3 Device Cap). While setup allows you to continue installing Windows Server 2012 (whether on Core or on GUI), your installation will not be successful and you will need to roll back your installation.
The solution is relatively simple: if you are on a full version of Windows Server, you simply go to device manager and you disable the offending "Microsoft Emulated S3 Device Cap" system device:
If you are on Server Core, obviously you would need to do the same from the command line. Entering the following command will disable the device:
sc delete s3cap
The system should then answer you with:
[SC] DeleteService SUCCESS
After rebooting your server, you can then restart the upgrade process. The Compatibility report will then give you a clean slate:
This allows you to successfully upgrade your server ...