NullReferenceException on SPWorkflowTask.AlterTask ()

In a custom task edit form for a custom content type, the following code is used to update the task item:

Hashtable taskHash = new Hashtable();
taskHash["Status"] = "Approved";
taskHash["PercentComplete"] = "1";
SPWorkflowTask.AlterTask(this._taskItem, taskHash, true);

This works great most of the time, however, if the custom content type defines no fieldrefs, or more specifically, the content type XML does not have the node, as could be the case if only a custom form is included in the custom content type, the following exception would be thrown on the AlterTask line:

System.NullReferenceException was unhandled by user code
Message="Object reference not set to an instance of an object."
Source="Microsoft.SharePoint"

To fix this cryptic error, make sure that the node is in the content type definition XML, even when there're no child nodes.

Debug ASPX pages added to /LAYOUTS in SharePoint

How do you debug an ASPX page added to SharePoint's /LAYOUTS folder? There are many situations where you need to drop ASPX pages in the /LAYOUTs folder as part of a custom solution to some requriements. For example, an edit form for a custom content type, or a page for displaying data in a special way.

If the page fails, the exception is most likely logged in SharePoint log in the 12 hives, but wouldn't it be nice if you can step through the page in debug mode? All you need to do is to add the attribute debug="true" in the Page directive, set the breakpoint and attach the debugger to the process in Visual Studio, and voila!

Of course this is the standard way to debug ASP.NET pages. Only if you can remember it in the muddy water of SharePoint.