Location in source:

Specifically, this.currentConnection is sometimes null when this line of code is executed.

I believe this can be fixed by changing this.currentConnection.DisconnectReason to this.DisconnectReason, which checks this.currentConnection for null.

Context: We're using Open3270 to automate a third-party terminal that sometimes experiences long response times. We need a way to interrupt Open3270 when this happens. We'd like the interruption to be immediate and graceful, if possible. Currently we interrupt the wait by calling TNEmulator.Close from a different thread. However, this causes the above line of code to be executed when this.currentConnection is null, masking the intended TNHostException.