ERROR ON CONSOLE WHILE ONE MINER CONNECTED 
Everything works fine , mining and payments 

but when one miner connects (others are fine )

i am getting the below error , i could not find any explanation 

[clo] [0HMQ1A9BCP8N8] Connection error: System.NullReferenceException: Object reference not set to an instance of an object.
   at Miningcore.Blockchain.Ethereum.EthereumPool.OnSubmitLoginAsync(StratumConnection connection, Timestamped`1 tsRequest) in /home/miningcore/src/Miningcore/Blockchain/Ethereum/EthereumPool.cs:line 339
   at Miningcore.Blockchain.Ethereum.EthereumPool.OnRequestAsync(StratumConnection connection, Timestamped`1 tsRequest, CancellationToken ct) in /home/miningcore/src/Miningcore/Blockchain/Ethereum/EthereumPool.cs:line 520
   at Miningcore.Stratum.StratumServer.OnRequestAsync(StratumConnection connection, JsonRpcRequest request, CancellationToken ct) in /home/miningcore/src/Miningcore/Stratum/StratumServer.cs:line 203
   at Miningcore.Stratum.StratumConnection.ProcessRequestAsync(CancellationToken ct, Func`4 onRequestAsync, ReadOnlySequence`1 lineBuffer) in /home/miningcore/src/Miningcore/Stratum/StratumConnection.cs:line 379
   at Miningcore.Stratum.StratumConnection.ProcessRequestAsync(CancellationToken ct, Func`4 onRequestAsync, ReadOnlySequence`1 lineBuffer) in /home/miningcore/src/Miningcore/Stratum/StratumConnection.cs:line 379
   at Miningcore.Stratum.StratumConnection.ProcessReceivePipeAsync(CancellationToken ct, TcpProxyProtocolConfig proxyProtocol, Func`4 onRequestAsync) in /home/miningcore/src/Miningcore/Stratum/StratumConnection.cs:line 281
