Hi @耀辉 林 ,
I am fairly certain that SCVMM does not support the Windows Server 20H2 version, therefore it doesn't recognize the version.
For the supported versions please refer to the official documentation over here:
System requirements for System Center Virtual Machine Manager
https://learn.microsoft.com/en-us/system-center/vmm/system-requirements?view=sc-vmm-2019#vmm-2019-system-requirements
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Best regards,
Leon