How to Fix Asp.net MVC Web Api HTTP PUT and DELETE requests failing

ASP.NET MVC 4 has a new feature called WebAPI which makes it much easier to create a REST API in ASP.NET. Unfortunately, I ran into one problem with IIS 6.0 that prevented the full REST spec from being used. By default IIS 6 wouldn't allow the PUT or DELETE verbs to be used with the WebAPI app that we created.

Page requests using GET and POST worked fine, but PUT and DELETE gave the following error:

Failed to load resource: the server responded with a status of 501 (Not Implemented)

In order to solve the issue I needed to add the ASP.NET 4.0 dll to the Wildcard mappings in the Configuration area on the Home Directory tab for the website. That fixed the problem for me. Here are the steps that I took to correct the issue in IIS.

1. Find the web site in the "Web Sites" folder in Internet Information Services (IIS) and right-click and select properties.

2. Go to the "Home Directory" tab and click the "Configuration..." button.

3. Find the .aspx extension in the "Application extensions" table, select it and press the "Edit..." button.

4. Copy the entire path and file name in the "Executable:" text box to the clipboard.  Press the "Cancel" button.

5. Press the "Insert..." button near the "Wildcard application maps" list box.  Paste the text from the clipboard into the "Executable:" text box and press "OK".

6. Press OK on the Application Configuration dialog and again on the website properties box.

That's it!  Hope that saves a few people some frustration :)