Use the VHDX format for virtual hard disks used in virtual machines that are enabled for replication with recovery history. ...

Use the VHDX format for virtual hard disks used in virtual machines that are enabled for replication with recovery history. The VHDX format has reliability mechanisms that help protect the disk from corruptions due to system power failures. You can convert a virtual hard disk from VHD format to VHDX format. However, do not convert the virtual hard disk if it is likely to be attached to an earlier release of Windows at some point. Windows releases earlier than {1} do not support the VHDX format.