I'm guessing that self.chosenMailData
is an observable, and if it is you should be setting it as a function, i.e. self.chosenMailData(newValue);
not as a property self.chosenMailData = newValue; //this will not work
. If it is not observable, then, of course, any binding wouldn't be updated since they wouldn't know that the value has changed.
The reason is that if you replace the observable property (not the observable value) all subscriptions will still be to the old observable which still has the old value.
Regarding the error, it states 500
which makes it sound like a server error, not a client side error.