How to Upgrade Failover Cluster Functional Level

When you add new nodes with a higher operating system to your Windows Failover cluster environment, you will receive warnings about "Functional Level" mismatch in your failover cluster logs.

The main reason for these warnings is that the operating systems and functional levels of the clusters connected to the nodes in your environment are different from each other.

You can follow the steps below to change the functional level compatibility;

  • To view the Failover Cluster Functional Level version
    Get-Cluster | select ClusterFunctionalLevel
  • To upgrade the Failover Cluster Functional Level version
  • To view the upgrade process of the Failover Cluster Functional Level version
    Get-Cluster | select ClusterFunctionalLevel
  • In Windows Server 2019 the Clustering team introduced a new PowerShell cmdlet to check how many nodes of the cluster are running on which level
    "Get-ClusterNodeSupportedVersion" helps you to identify the Cluster Functional Level and the Cluster Upgrade Version.

The table below shows the values and each corresponding functional level:


For more detailed information;

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How to In-Place Upgrade Windows Server 2016 to Windows Server 2019 ?

What is the in-place upgrade?
In the simplest terms, it is the process of upgrading your Windows operating system without losing your data.

If you are going to do this on a physical server, it is useful to check the hardware compatibility first.
Hardware requirements for Windows Server

You can also see the version transitions of the operating systems in the table below.

If your server is located on a virtual platform, it is useful to take a snapshot/checkpoint before doing the in-place upgrade.

After connecting the “Windows Server 2019” .iso file to your server with the “Windows Server 2016” operating system, "setup.exe" should be run.

On the next screen, we are asked whether to install the updates. The recommended action here is to make updates, and we continue by ticking this option.

Select the windows version.

Select Accept to accept the terms of your licensing agreement

Attention! Since our preference is an in-place upgrade, we continue with the "Keep personal files and apps" option.

Depending on the size of your data, the in-place upgrade process may take an average of 30 minutes to 1 hour.


If you have a server with the "Windows Server 2012 R2" operating system, you can’t upgrade directly to “Windows Server 2019”.
You will upgrade  "Windows Server 2016" first, then you can upgrade to "Windows Server 2019".


Ps: Disable UAC before starting the in-place upgrade, then enable it again.

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