When you try to add a Storage Spaces Direct (S2D) or Scale-Out File Server (SOFS) cluster to the storage fabric in a Microsoft System Center 2016 Virtual Machine Manager (VMM) cluster, you receive the following error message:
Error (26311)
Registration of the storage subsystem <CLUSTER> for user <ACCOUNT> failed from <VMM NODE> with error code 1 [SM_RC_NOT_SUPPORTED].
Recommended Action
Specify a valid subsystem name, and user credentials for registering the subsystem.