If you were using DropDownListFor
like this:
@Html.DropDownListFor(m => m.SelectedItemId, Model.MySelectList)
where MySelectList
in the model was a property of type SelectList
, this error could be thrown if the property was null
.
Avoid this by simply initializing it in constructor, like this:
public MyModel()
{
MySelectList = new SelectList(new List<string>()); // empty list of anything...
}
This often happens in POST
actions. Make sure you assign something before re-rendering the view.