OnMatchDestroy not existing in 5.3.3?

I would like to use the callback OnMatchDestroy, but it does not seem to exist anymore in 5.3.3..?

Code (CSharp):

1. public override void OnLobbyServerDisconnect(NetworkConnection conn){
2.    if (isHost) {
3.             NetworkManager.singleton.matchMaker.DestroyMatch (m_networkId, OnMatchDestroy);
4.    }
5.    else {
6.             DropConnectionRequest dropReq = new DropConnectionRequest ();
7.             dropReq.networkId = (NetworkID)this.m_networkId;
8.            dropReq.nodeId = (NodeID)this.m_nodeId;
9.            NetworkManager.singleton.matchMaker.DropConnection (dropReq);
10. }
11. }

But I get The name `OnMatchDestroy' does not exist in the current context...
Any idea?