WebAPI Delete Causing 500 / Object Not Found - rest

Question

I am trying to implement a WebAPI 2, using C#. Everything is working fine on my development setup, but when I deploy it to the live server, the DELETE function is causing an error.
I've stripped the function right to the basics, and still it causes an error. All other API calls continue to work fine.
The code is:
[HttpDelete]
public string Delete(int id)
{
return "delete";
}
The error is:
<div id="content">
<div class="content-container"><fieldset>
<h2>500 - Internal server error.</h2>
<h3>There is a problem with the resource you are looking for, and it cannot be displayed.</h3>
</fieldset></div>
</div>
<Error>
<Message>An error has occurred.</Message>
<ExceptionMessage>
Object reference not set to an instance of an object.
</ExceptionMessage>
<ExceptionType>System.NullReferenceException</ExceptionType>
<StackTrace>
at System.Web.Http.ApiController. <InvokeActionWithExceptionFilters>d__1.MoveNext() --- End of stack trace from previous location where exception was thrown --- at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) at System.Web.Http.Dispatcher.HttpControllerDispatcher. <SendAsync>d__0.MoveNext()
My web.config is as follows:
<?xml version="1.0" encoding="utf-8"?>
<!--
For more information on how to configure your ASP.NET application, please visit
http://go.microsoft.com/fwlink/?LinkId=301879
-->
<configuration>
<connectionStrings>
<add name="PlaneLoggerEntities" connectionString="metadata=res://*/Models.Model.csdl|res://*/Models.Model.ssdl|res://*/Models.Model.msl;provider=System.Data.SqlClient;provider connection string="data source=.\MSSQLSERVER2012;initial catalog=PlaneLogger_Dev;integrated security=True;pooling=False;multipleactiveresultsets=True;App=EntityFramework"" providerName="System.Data.EntityClient" />
<add name="PlaneRegistrationsEntities" connectionString="metadata=res://*/Models.Aircraft.csdl|res://*/Models.Aircraft.ssdl|res://*/Models.Aircraft.msl;provider=System.Data.SqlClient;provider connection string="data source=.\MSSQLSERVER2012;initial catalog=PlaneRegistrations;integrated security=True;multipleactiveresultsets=True;App=EntityFramework"" providerName="System.Data.EntityClient" />
</connectionStrings>
<appSettings>
<add key="webpages:Version" value="3.0.0.0" />
<add key="webpages:Enabled" value="false" />
<add key="ClientValidationEnabled" value="true" />
<add key="UnobtrusiveJavaScriptEnabled" value="true" />
</appSettings>
<system.web>
<compilation targetFramework="4.5" />
<httpRuntime targetFramework="4.5" />
</system.web>
<system.webServer>
<modules>
<add name="BasicAuthHttpModule" type="PlaneLogger.API.Modules.BasicAuthHttpModule" />
<remove name="WebDAVModule"/>
</modules>
<handlers>
<remove name="ExtensionlessUrlHandler-Integrated-4.0" />
<remove name="OPTIONSVerbHandler" />
<remove name="TRACEVerbHandler" />
<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>
<runtime>
<assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
<dependentAssembly>
<assemblyIdentity name="System.Web.Helpers" publicKeyToken="31bf3856ad364e35" />
<bindingRedirect oldVersion="1.0.0.0-3.0.0.0" newVersion="3.0.0.0" />
</dependentAssembly>
<dependentAssembly>
<assemblyIdentity name="System.Web.Mvc" publicKeyToken="31bf3856ad364e35" />
<bindingRedirect oldVersion="1.0.0.0-5.0.0.0" newVersion="5.0.0.0" />
</dependentAssembly>
<dependentAssembly>
<assemblyIdentity name="System.Web.Optimization" publicKeyToken="31bf3856ad364e35" />
<bindingRedirect oldVersion="1.0.0.0-1.1.0.0" newVersion="1.1.0.0" />
</dependentAssembly>
<dependentAssembly>
<assemblyIdentity name="System.Web.WebPages" publicKeyToken="31bf3856ad364e35" />
<bindingRedirect oldVersion="1.0.0.0-3.0.0.0" newVersion="3.0.0.0" />
</dependentAssembly>
<dependentAssembly>
<assemblyIdentity name="WebGrease" publicKeyToken="31bf3856ad364e35" />
<bindingRedirect oldVersion="1.0.0.0-1.5.2.14234" newVersion="1.5.2.14234" />
</dependentAssembly>
</assemblyBinding>
</runtime>
</configuration>
Please help, it's doing my nut in now!

Answer 1

Crosscheck following:
1. Are you really passing int values as id.
2. Is Cors policy enabled on Delete method'c controller.
3. Are you sending any data object in body, If yes then check its correctness with corresponding class.
4. use ( [FromRoute] int Id) as parameter.
I hope it will work for you.

Answer 2

After some digging, I have managed to find the answer.
Basically, the problem was due to how IIS handles modules and request handlers. By default, WebDAV will be configured to listen to PUT and DELETE requests. Normally WebDAV will be disabled on your server, however this doesn't remove the bindings, any PUT and DELETE requests will still be passed to WebDAV, which will reject them due to it being disabled.
You need to remove WebDAV via the web config, as follows:
<modules>
<remove name="WebDAVModule"/>
</modules>
<handlers>
<remove name="WebDAV" />
</handlers>
You need both of these entries for it to work. I only had the remove module entry in my web.config.