Problem in authority shifting of non-player object - unity3d

Question

I am making a multiplayer game and I want to have player to interact with a non-player object (whose transform can be changed by any player). When I interact them with the player who joined first (or the guy who is hosting) its working but if I try to interact it with the another player (the one who joined second) the objects goes back to the location that the first player left him at.
So what I tried is to shift the authority of non-player object but I am having the following errors.
Anyone is having the same issue or knows any other way to do the above task? I am using the following code to change the authority:
[Command]
void Cmd_AssignLocalAuthority(GameObject obj)
{
print("shifting authority successfully");
NetworkInstanceId nIns = obj.GetComponent<NetworkIdentity>().netId;
GameObject client = NetworkServer.FindLocalObject(nIns);
NetworkIdentity ni = client.GetComponent<NetworkIdentity>();
ni.AssignClientAuthority(connectionToClient);
}
[Command]
void Cmd_RemoveLocalAuthority(GameObject obj)
{
print("reverting authority successfully");
NetworkInstanceId nIns = obj.GetComponent<NetworkIdentity>().netId;
GameObject client = NetworkServer.FindLocalObject(nIns);
NetworkIdentity ni = client.GetComponent<NetworkIdentity>();
ni.RemoveClientAuthority(ni.clientAuthorityOwner);
}
And the error I am getting is this

Answer 1

You need to know that the changes SHOULD be called from a player object, not the object itself, as it do not have authority.
For setting authority you should do something like this:
[Command]
public void CmdSetAuth(NetworkInstanceId objectId, NetworkIdentity player)
{
GameObject iObject = NetworkServer.FindLocalObject(objectId);
NetworkIdentity networkIdentity = iObject.GetComponent<NetworkIdentity>();
//Checks if anyone else has authority and removes it and lastly gives the authority to the player who interacts with object
NetworkConnection otherOwner = networkIdentity.clientAuthorityOwner;
if (otherOwner == player.connectionToClient)
{
return;
}
else
{
if (otherOwner != null)
{
networkIdentity.RemoveClientAuthority(otherOwner);
}
networkIdentity.AssignClientAuthority(player.connectionToClient);
}
networkIdentity.AssignClientAuthority(player.connectionToClient);
}