Known Issues during an upgrade
Issue 1: Compatibility Report shows errors that certain roles are installed even when they are not
During the Windows upgrade, the Upgrade Compatibility wizard runs a through test of the machine and reports any known compatibility issues. Sometime, the report may show you a particular role installed when it is actually not present.
One of the reasons this occurs is due to corruption in the component store, or any registry locations related to the role, that is causing the state of the role to be misreported. In this scenario, CheckSUR shows that there were several missing Deployment Keys in the components hive.
Since there is no easy way to fix links to so many keys, we ended up performing an in-place upgrade of Windows Server 2008 R2 using the media. This fixed the issue with the missing registry entries in the components hive and we could verify that running CheckSUR fixed the issue. Once we made sure that the state of all the components and deployment manifests were intact, we could perform the upgrade to Windows Server 2012 without any issues.
Issue 2: Upgrade fails when there is another volume larger than the C drive on the same disk without a drive letter.
Consider a partition layout as shown below:
The computer could be configured this way for various reasons. For examples, you are having a dual-boot system, and you do not want to have a drive letter for the other system drive. Or, the computer manufacturer configures this volume to store recovery data. In this scenario, the upgrade process fails after the first restart. Additionally, you receive the following error message: Setup cannot continue. Your computer will now restart, and your previous version of Windows will be restored.
In this situation, the setup process temporarily assigns a drive letter to that volume and may use this volume to hold temporary files ($Windows.~BT) because that is the largest volume. But the temporary drive letter assignment is removed during the reboot and it leaves the upgrade without a temporary file location causing it to fail.
This is very unlikely on a server to have this sort of partition layout, but if you dual boot your client desktop, you may run into this issue. The workaround is simple, just statically assign a drive letter to any additional partitions you have on the disk, except for the System Reserved partition.
Joseph Conway had written the blog “General guidance before installing Service Pack 1 for Windows 7 and Windows 2008 R2” a while back discussing guidance installing Service Packs. The same guidance also applies when performing Server upgrades. Here are some additional things you should keep in mind when upgrading to Windows Server 2012:
On a side note: CheckSUR is no longer needed on Windows 8 and Windows Server 2012. The number of instances where CheckSUR has fixed CBS corruption was so large, that we decided to include the tool inbox. For more details on inbox corruption repair feature available in Windows 8, check this “Fixing component store corruption in Windows 8 and Windows Server 2012”.
The last tip for today – is to pay attention to the errors and warnings during setup. There are significant improvements in the logging as well. If you run into an issue during setup, the SetupAct and SetupErr logs will give you more details. For a complete list of log file check this TechNet article: http://technet.microsoft.com/en-us/library/hh824819.aspx.
Also watch out for more posts in this series.
Regards, Vimal Shekar Windows Core Team @ Microsoft