ExtensionlessUrlHandler and "Recursion too deep; the stack overflowed" - asp.net-web-api

Question

I'm trying to get a fellow developer's app working on my machine. Solution is built in VS 2015 using Web API and I'm running it using 64-bit IIS Express. Every request is returning 500.0 errors. Request tracing log says this about it:
1517. -MODULE_SET_RESPONSE_ERROR_STATUS
ModuleName ManagedPipelineHandler
Notification EXECUTE_REQUEST_HANDLER
HttpStatus 500
HttpReason Internal Server Error
HttpSubStatus 0
ErrorCode Recursion too deep; the stack overflowed. (0x800703e9)
ConfigExceptionInfo
The relevant config section looks like this:
<system.webServer>
<handlers>
<remove name="OPTIONS" />
<remove name="OPTIONSVerbHandler" />
<remove name="TRACEVerbHandler" />
<remove name="ExtensionlessUrlHandler-Integrated-4.0" />
<remove name="ExtensionlessUrlHandler-ISAPI-4.0_32bit" />
<remove name="ExtensionlessUrlHandler-ISAPI-4.0_64bit" />
<add name="ExtensionlessUrlHandler-ISAPI-4.0_32bit" path="*" verb="*" 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="*" 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="*" type="System.Web.Handlers.TransferRequestHandler" preCondition="integratedMode,runtimeVersionv4.0" />
</handlers>
</system.webServer>
Other possibly relevant facts:
The machine hasn't been used for web hosting before, but I've been doing a lot of VS2013 development and only installed 2015 last week to run this project.
The project does contain some C# 6.0 features, namely the new string interpolation goodies.
How would I even begin to debug this? I'm getting zero relevant hits on Google.

Answer 1

Change path="*" to path="*." in each of the handlers you have listed.
<add name="ExtensionlessUrlHandler-ISAPI-4.0_32bit" path="*." verb="*" 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="*" 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="*" type="System.Web.Handlers.TransferRequestHandler" preCondition="integratedMode,runtimeVersionv4.0" />
I believe there is a way to use path="" but I haven't figured out what it is. I just ran across this question because I was trying to use path="" and that's when the "recursion too deep..." error was thrown.

Answer 2

I had the exact same issue when migrating my projects to VS2017 (Was working in VS2010) and managed to resolve this by following the recommendation from another post:
https://stackoverflow.com/a/29370225
So the issue is that the IISExpress uses a different handler name (without the "Handler" postfix) from IIS, so you will need to add the following removal scripts to the web.config instead:
<!--Handler in IIS-->
<remove name="ExtensionlessUrlHandler-ISAPI-4.0_32bit"/>
<remove name="ExtensionlessUrlHandler-ISAPI-4.0_64bit"/>
<remove name="ExtensionlessUrlHandler-Integrated-4.0"/>
<!--Handler in IISExpress-->
<remove name="ExtensionlessUrl-ISAPI-4.0_32bit" />
<remove name="ExtensionlessUrl-Integrated-4.0" />
Hopefully this helps.