Purpose: This process will upgrade the infrastructure underlying the ADFS system to Windows Server 2019. This brings more efficient services as well has enhancements related to MFA.
Impact: This is a non-interruptive action. The new nodes will be added into the farm, taking over the same functionality. Once all nodes are replaced with the Server 2019 nodes, we can upgrade the ADFS farm function to 2019.
Affected: This will have minimal impact as the configuration of ADFS is shared among all nodes in the farm. There is also no outage during this process.