renderpartial with null model gets passed the wrong type

Andrew I think the problem you are getting is a result of the RenderPartial method using the calling (view)'s model to the partial view when the model you pass is null.. you can get around this odd behavior by doing:

<% Html.RenderPartial("TaskList", Model.Tasks, new ViewDataDictionary()); %>

Does that help?

@myandmycode's answer is good, but a slightly shorter one would be

<% Html.RenderPartial("TaskList", new ViewDataDictionary(Model.Tasks)); %>

This works because the ViewDataDictionary is the thing that holds the model, and it can accept a model as a constructor parameter. This basically passes an "entire" view data dictionary, which of course only contains the possibly-null model.