iis - ASP.Net Core CreatedAtAction in HttpPost action returns 201 but entire request ends with 500 -

i'm following[1] setting first .net core webapi (moving "old" webapi). when httppost action, in tutorial:

[httppost] public iactionresult create([frombody] todoitem item) {     if (item == null)     {         return badrequest();     }     todoitems.add(item);     return createdataction("gettodo", new { id = item.key }, item); } 

i httperror 500 after exiting controller. createdataction returns proper object status code 201 expect, , after method exits server somehow turns 500. don't seem able step rest of pipeline. trace gives me following error:

81.  -general_request_entity  82.  -notify_module_completion  83.  -module_set_response_error_status [warning] 171ms        modulename          aspnetcoremodule        notification        execute_request_handler        httpstatus          500        httpreason          internal server error        httpsubstatus       0        errorcode           operation completed successfully. (0x0)        configexceptioninfo 

everything (program.cs, startup.cs) set in[1]. behaves same in iisexpress (vs2015 update 3) , iis7.5 (windows 7). other return types, 200 (with new objectresult(item) get, 404 notfound() or 204 nocontentresult() put work ok. seems it's problem 201 somehow. ideas?

[1] https://docs.asp.net/en/latest/tutorials/first-web-api.html

update posting additional details per request:

startup.cs:

using system; using system.collections.generic; using system.linq; using system.threading.tasks; using firstwebapi.models; using microsoft.aspnetcore.builder; using microsoft.aspnetcore.hosting; using microsoft.extensions.configuration; using microsoft.extensions.dependencyinjection; using microsoft.extensions.logging;  namespace firstwebapi {     public class startup     {         public startup(ihostingenvironment env)         {             var builder = new configurationbuilder()                 .setbasepath(env.contentrootpath)                 .addjsonfile("appsettings.json", optional: true, reloadonchange: true)                 .addjsonfile($"appsettings.{env.environmentname}.json", optional: true)                 .addenvironmentvariables();             configuration = builder.build();         }          public iconfigurationroot configuration { get; }          // method gets called runtime. use method add services container.         public void configureservices(iservicecollection services)         {             services.addmvc();             services.addlogging();             services.addsingleton<itodorepository, todorepository>();         }          // method gets called runtime. use method configure http request pipeline.         public void configure(iapplicationbuilder app, ihostingenvironment env, iloggerfactory loggerfactory)         {             loggerfactory.addconsole(configuration.getsection("logging"));             loggerfactory.adddebug();              app.usedeveloperexceptionpage();             app.usestatuscodepages();              app.usemvc();            }     } } 

todocontroller.cs:

using system.collections.generic; using firstwebapi.models; using microsoft.aspnetcore.mvc;  namespace firstwebapi.controllers {     [route("api/[controller]")]     public class todocontroller : controller     {         public todocontroller(itodorepository todoitems)         {             todoitems = todoitems;         }         public itodorepository todoitems { get; set; }          public ienumerable<todoitem> getall()         {             return todoitems.getall();         }          [httpget("{id}", name = "gettodo")]         public iactionresult getbyid(string id)         {             var item = todoitems.find(id);             if (item == null)             {                 return notfound();             }             return new objectresult(item);         }          [httppost]         public iactionresult create([frombody] todoitem item)         {             if (item == null)             {                 return badrequest();             }             todoitems.add(item);             return createdataction("gettodo", new { id = item.key }, item);         }          [httpput("{id}")]         public iactionresult update(string id, [frombody] todoitem item)         {             if (item == null || item.key != id)             {                 return badrequest();             }              var todo = todoitems.find(id);             if (todo == null)             {                 return notfound();             }              todoitems.update(item);             return new nocontentresult();         }          [httpdelete("{id}")]         public void delete(string id)         {             todoitems.remove(id);         }     } } 

update 2

turns out, createataction 201 tries redirect unhandled route:

system.invalidoperationexception: no route matches supplied values.    @ microsoft.aspnetcore.mvc.createdatactionresult.onformatting(actioncontext context) 

still not sure why tho, method getbyid should mapped gettodo per controller settings.

so, after bit of debugging found caused it. turned out this.url.action("get", "gettodo", new { id=item.key }) return null , 500 came fact iis not match route attached 201.

as turns out, either need setup:

app.usemvc(routes => {     routes.maproute(         name: "default",         template: "{controller}/{action}"); }); 

or use createatroute.