CryptoExchange.Net/docs/FAQ.md

title, nav_order

title	nav_order
FAQ	9

I occasionally get a NullReferenceException, what's wrong?

You probably don't check the result status of a call and just assume the data is always there. NullReferenceExecptions will happen when you have code like this var symbol = client.GetTickersAync().Result.Data.Symbol because the Data property is null when the call fails. Instead check if the call is successful like this:

var tickerResult = await client.GetTickersAync();
if(!tickerResult.Success)
{
  // Handle error
}
else
{
  // Handle result, it is now safe to access the Data property
  var symbol = tickerResult.Data.Symbol;
}

The socket client stops sending updates after a little while

You probably didn't keep a reference to the socket client and it got disposed. Instead of subscribing like this:

private void SomeMethod()
{
  var socketClient = new BinanceSocketClient();
  socketClient.Spot.SubscribeToOrderBookUpdates("BTCUSDT", data => {
	// Handle data
  });
}

Subscribe like this:

private BinanceSocketClient _socketClient = new BinanceSocketClient();

// .. rest of the class

private void SomeMethod()
{
  _socketClient.Spot.SubscribeToOrderBookUpdates("BTCUSDT", data => {
	// Handle data
  });
}