I would like to try to add a Server 2012 Hyper-V server to my current cluster,

Currently 2 server 2016 Hyper-V servers clustered.

I need to be able to add the third because I have to do some reconfiguration on the cluster, I have to be able to Live Migrate the couple of VM's to the new 2012 server take both 2016 servers out of the cluster fix them and then add them back.

When I try to add the Server 2012 server I get an error:

* The server 'Server.domain.com' could not be added to the cluster. An error occurred while adding node 'Server.domain.com' to cluster 'ClusterName'.

The node failed to join the cluster because the joining node and other nodes in the cluster have incompatible operating system versions. To get more information about operating system versions of the cluster, run the Validate a Configuration Wizard or the Test-Cluster Windows PowerShell cmdlet

Googling this error looks like because the Cluster Fucntional Level is 9 and i think I can get it 8 i might be able to add it.

However the current run level is 9.

How can I downgrade the cluster functional level from 9 to 8?

  • 1
    Why not add more modern resources? I find your approach odd. Maybe if you explained why you're doing this I could provide more useful input. However, from what I already know of HyperV, I don't think this can be done without rebuilding your cluster. This is fairly expected, as I don't expect devs to put in effort into downgrading clusters when upgrading is tricky enough as it is. – Spooler Aug 3 '17 at 18:15
  • What OS are you running in the failover cluster now? members of a Microsoft failover cluster must run the same Operating system (unless we are talking Server 2016) – Michael Brown Aug 3 '17 at 18:31
  • @SmallLoanOf1M Updated question – Anthony Fornito Aug 3 '17 at 19:03

After doing some research, it looks like you can't downgrade cluster functional levels, nor can you live migrate instances from 2016 to 2012 anyways. I would suggest using server 2016 instead of a 2012 to get this job done. You'd have to put a lot of work into using the wrong tool for the job if you were to try to use 2012 for this, even if downgrading was supported.

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