Up until now, upgrading the operating system (in-place) of a Configuration Manager site server or site system was strictly unsupported – that doesn’t of course mean it didn’t work, just that Microsoft never planned or designed for it and ultimately never tested it so all results and consequences of doing so were yours (and yours alone) to own and fix.

Well, thanks to someone in the product group, this has changed. The documentation team recently published an update (not sure when – could have actually been there a while and I just didn’t know about it) that Nicolai Henriksen and Panu Saukko brought to my attention. This isn’t a free for all and there are caveats as documented on TechNet; here’s an excerpt from  http://technet.microsoft.com/en-us/library/gg682077.aspx#BKMK_UpgradeInfrastructure:

Configuration Manager supports an in-place upgrade of the operating system of the site server in the following situations:

  • In-place upgrade to a higher Windows Server service pack as long as the resulting service pack level remains supported by Configuration Manager.
  • In-place upgrade from Windows Server 2012 to Windows Server 2012 R2.

Configuration Manager does not support the following Windows Server upgrade scenarios.

  • Any version of Windows Server 2008 to any version of Windows Server 2008 R2 or later.
  • Any version of Windows Server 2008 to any version of Windows Server 2012 or later.
  • Any version of Windows Server 2008 R2 to any version of Windows Server 2012 or later.

I just put this revelation to the test in my lab and although I certainly can’t put it through it’s complete paces, it’s looking good so far except one hiccup. Upgrading the OS also upgrades WSUS which requires the post-installation tasks that configure the DB and content path to be performed again: this can easily be done from server manager or by launching the WSUS admin console. Once I did that, everything was green again. Note that I spotted this issue by checking the site status in the console and then reviewing the appropriate status messages and logs (which you should always do after performing any type of change like this).

One thing I did do before the upgrade is to stop and disable all of the ConfigMgr related services. This was partially a speed thing and partially a paranoia thing – I had a 2012 to 2012 R2 OS upgrade rollback on one of my lab SQL servers at one point that I resolved by disabling SQL services before starting the upgrade. So, not necessarily a strict recommendation or even a good practice, just something that I did for warm fuzzies.