i got an master server connecting problem how can i solve this ?

Operation failed: OperationResponse 227: ReturnCode: -1 (Unknown operation code 227). Parameters: {} Server: MasterServer
UnityEngine.Debug:LogError(Object)
NetworkingPeer:OnOperationResponse(OperationResponse) (at Assets/Photon Unity Networking/Plugins/PhotonNetwork/NetworkingPeer.cs:1547)
ExitGames.Client.Photon.PeerBase:DeserializeMessageAndCallback(Byte[])
ExitGames.Client.Photon.EnetPeer:DispatchIncomingCommands()
ExitGames.Client.Photon.PhotonPeer:DispatchIncomingCommands()
PhotonHandler:Update() (at Assets/Photon Unity Networking/Plugins/PhotonNetwork/PhotonHandler.cs:157)