EDIT: Update to the latest version of WebAPI currently 5.2.7 (https://www.nuget.org/packages/Microsoft.AspNet.WebApi/)
ORIGINAL:
If you cannot use instead:
new HttpMethod("PATCH")
See the following example use in Web API source code
EDIT: Update to the latest version of WebAPI currently 5.2.7 (https://www.nuget.org/packages/Microsoft.AspNet.WebApi/)
ORIGINAL:
If you cannot use instead:
new HttpMethod("PATCH")
See the following example use in Web API source code