Scripting Reference
MonoBehaviour.OnFailedToConnectToMasterServer

function OnFailedToConnectToMasterServer (error : NetworkConnectionError) : void

Description

Called on clients or servers when there is a problem connecting to the MasterServer.

The reason for the error is passed in as a NetworkConnectionError enum.

JavaScript 
function OnFailedToConnectToMasterServer(info :    NetworkConnectionError) {
    Debug.Log("Could not connect to master server: "+ info);
}
using UnityEngine;
using System.Collections;

public class example : MonoBehaviour {
    void OnFailedToConnectToMasterServer(NetworkConnectionError info) {
        Debug.Log("Could not connect to master server: " + info);
    }
}
import UnityEngine
import System.Collections

class example(MonoBehaviour):

    def OnFailedToConnectToMasterServer(info as NetworkConnectionError):
        Debug.Log(('Could not connect to master server: ' + info))