Assume that you apply September cumulative update KB 4038782 to a server that's running Windows Server 2016 and is a member of the Storage Spaces Direct cluster. When you run the Get-PhysicalDisk cmdlet, some disks may display an operational status of "In Maintenance Mode." The Get-VirtualDisk cmdlet may also display the operational status of the virtual disk as "Degraded."
This issue occurs because the September cumulative update introduces a change to the logic of the Suspend-ClusterNode and Resume-ClusterNode cmdlets to exclude putting disks in maintenance mode or removing them from maintenance mode. When you do a rolling upgrade between binary versions, differing behavior may occur among the nodes that are updated, leaving some disks in Storage Maintenance Mode.
Note Cluster Aware Updating (CAU) uses the Suspend-ClusterNode and Resume-ClusterNode cmdlets and will also encounter this issue.
To fix this issue, run the following PowerShell command to remove the disks from maintenance mode:
Get-PhysicalDisk | ? OperationalStatus -eq "In Maintenance Mode" | Disable-StorageMaintenanceMode
Note After all nodes are updated to the September update or a later update, this issue will not occur.