So i just setup a new Azure Stack HCI cluster on Windows Server 2019 with the September Cumulative Update and it was throwing a We couldn’t complete the features Undoing changes Don’t turn off your computer.
When i install new clusters/nodes i always run a script to set customizations and one of those is installing Hyper-V, Failover Clustering, Datacenter Bridging and more. And up untill now this has worked fine adding all these at the same time with add-windowsfeature then adding all the feature names. At the end it would restart.
With the september Cumulative Update this did not work. I tried with a prev version and it worked find.
What i had to do was split the add-windowsfeature commandlet and install Hyper-V first, have the script loop a reboot, then install the rest of the features and do another reboot. As both Hyper-V and Failover Clustering now requires a reboot.
This has not been confirmed as a bug. But i have tested this now on 8 diffrent servers with the sept CU and it happens on all of them.