{
    objectType: 6
    name: "NewZone"
    parentId: 1
}

We are setting parentId = 1, because the object "Entire Network" has object id 1. This returns an "Internal error" with code 46.

I did take a look at the code and it seems impossible to create a node with parentId = 1.
https://github.com/netxms/netxms/blob/62c5f9ec1837c93023a40a71781ea2c73037b4c9/src/client/nxapisrv/java/src/main/java/org/netxms/websvc/handlers/Objects.java#L377

Can you check this?