Hi anonymous user,
While in-place upgrades are officially supported, the recommended method is to clean install and migrate your data/roles to the new server, as in-place upgrades can have various of issues.
A few things to check:
- Make sure the server does not have any pending reboots.
- Make sure your Windows Server 2008 R2 server is fully patched.
- Make sure your Windows Server 2008 R2 server does not have any software such as an antivirus or antimalware that may prevent the upgrade.
You can also follow the official documentation below and follow the "Before you begin your in-place upgrade" section:
Upgrade Windows Server 2008 R2 to Windows Server 2012 R2
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