Asp.NET Web API - 405 - HTTP verb used to access this page is not allowed - how to set handler mappings

You don't need to uninstall WebDAV, just add these lines to the web.config:

<system.webServer>
  <modules>
    <remove name="WebDAVModule" />
  </modules>
  <handlers>
    <remove name="WebDAV" />
  </handlers>
</system.webServer>

Common cause for this error is WebDAV. Make sure you uninstall it.

Change Your Web.Config file as below

 <system.webServer>
<validation validateIntegratedModeConfiguration="false"/>
<modules runAllManagedModulesForAllRequests="true">
<remove name="WebDAVModule" />
</modules>
<handlers>
<remove name="WebDAV"/>
<remove name="ExtensionlessUrlHandler-Integrated-4.0"/>
<remove name="OPTIONSVerbHandler"/>
<remove name="TRACEVerbHandler"/>
<add name="ExtensionlessUrlHandler-Integrated-4.0" path="*." verb="*" type="System.Web.Handlers.TransferRequestHandler" preCondition="integratedMode,runtimeVersionv4.0" />
</handlers>
</system.webServer>