If you build ASP.NET Web API services and are testing against IIS, you might encounter the following error when trying to execute a HTTP PUT or DELETE:
Searching the web actually yielded a ton of results but as usual they were wide and plentiful making it difficult to discern the correct solution. I'm using VS.NET 2012 and VS.NET 2013 on Windows 7 and Windows 8 (variations of these), so this solution is current.
Here it is: a combination of updating the values for a few of the HTTP Handlers and modules in the web.config will solve this issue. 1st the solution, which resides within the <system.webServer> section within the web.config file for the Web API project:
<system.webServer> <validation validateIntegratedModeConfiguration="false" /> <modules> <remove name="WebDAVModule" /> </modules> <handlers> <remove name="WebDAV" /> <remove name="ExtensionlessUrlHandler-ISAPI-4.0_32bit" /> <remove name="ExtensionlessUrlHandler-ISAPI-4.0_64bit" /> <remove name="ExtensionlessUrlHandler-Integrated-4.0" /> <add name="ExtensionlessUrlHandler-ISAPI-4.0_32bit" path="*." verb="GET,HEAD,POST,DEBUG,PUT,DELETE,PATCH,OPTIONS" modules="IsapiModule" scriptProcessor="%windir%\Microsoft.NET\Framework\v4.0.30319\aspnet_isapi.dll" preCondition="classicMode,runtimeVersionv4.0,bitness32" responseBufferLimit="0" /> <add name="ExtensionlessUrlHandler-ISAPI-4.0_64bit" path="*." verb="GET,HEAD,POST,DEBUG,PUT,DELETE,PATCH,OPTIONS" modules="IsapiModule" scriptProcessor="%windir%\Microsoft.NET\Framework64\v4.0.30319\aspnet_isapi.dll" preCondition="classicMode,runtimeVersionv4.0,bitness64" responseBufferLimit="0" /> <add name="ExtensionlessUrlHandler-Integrated-4.0" path="*." verb="GET,HEAD,POST,DEBUG,PUT,DELETE,PATCH,OPTIONS" type="System.Web.Handlers.TransferRequestHandler" preCondition="integratedMode,runtimeVersionv4.0" /> </handlers> </system.webServer>The explanation:
- The default ExtensionlessUrlHandler-* handlers displayed above are set within the %userprofile%\documents\iisexpress\config\applicationhost.config file and do not by default allow HTTP PUT and DELETE verbs. By removing and re-adding the handlers with all of the HTTP verbs we will allow, processing will continue as expected.
- Unfortunately updating the handlers is not enough. The WebDAV HTTP Publishing feature will block HTTP PUT and DELETE calls regardless of our previous modifications. WebDAV is a feature allowing access to files and folders via the internet as an alternative to FTP. If you are not using it in the Web API project, then removing the module will free up the restriction on these HTTP verbs. If you want to read more about what WebDAV is, please read this.