A routed "MS_attributerouteWebApi" is already in the route collection. Route names must be unique (Sitecore 9.0.1) [duplicate]

Question

i have a similar question to [A route named x is already in the route collection][1] [1]: A route named x is already in the route collection. Route names must be unique. But the solution mentioned there doesn't worked for me. In my solution (for Sitecore 9.0.1), i just added an Api Controller for PoC and deleted later again, and since then i'm not able to run Sitecore. Consider, that i don't have a Global.asax file or App_start Folder.

Could some one help me? I will appreciate it. Thanks.

Best Regards

+++++++++++ Displayed Error +++++++++++

Server Error in '/' Application. A route named 'MS_attributerouteWebApi' is already in the route collection. Route names must be unique. Parameter name: name Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.ArgumentException: A route named 'MS_attributerouteWebApi' is already in the route collection. Route names must be unique. Parameter name: name

Source Error:

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

Stack Trace:

[ArgumentException: A route named 'MS_attributerouteWebApi' is already in the route collection. Route names must be unique. Parameter name: name] System.Web.Routing.RouteCollection.Add(String name, RouteBase item) +391
System.Web.Http.Routing.AttributeRoutingMapper.MapAttributeRoutes(HttpConfiguration configuration, IInlineConstraintResolver constraintResolver, IDirectRouteProvider directRouteProvider) +166
Sitecore.Services.Infrastructure.Web.Http.HttpConfigurationBuilder.MapHttpAttributeRoutes() +89 Sitecore.Services.Infrastructure.Web.Http.ServicesConfigurator.Configure(HttpConfiguration config, RouteCollection routes) +501
Sitecore.Services.Infrastructure.Sitecore.Pipelines.ServicesWebApiInitializer.Process(PipelineArgs args) +194 (Object , Object[] ) +74
Sitecore.Pipelines.CorePipeline.Run(PipelineArgs args) +469
Sitecore.Pipelines.DefaultCorePipelineManager.Run(String pipelineName, PipelineArgs args, String pipelineDomain) +22
Sitecore.Nexus.Web.HttpModule.Application_Start() +161
Sitecore.Nexus.Web.HttpModule.Init(HttpApplication app) +764
System.Web.HttpApplication.RegisterEventSubscriptionsWithIIS(IntPtr appContext, HttpContext context, MethodInfo[] handlers) +581
System.Web.HttpApplication.InitSpecial(HttpApplicationState state, MethodInfo[] handlers, IntPtr appContext, HttpContext context) +172
System.Web.HttpApplicationFactory.GetSpecialApplicationInstance(IntPtr appContext, HttpContext context) +418
System.Web.Hosting.PipelineRuntime.InitializeApplication(IntPtr appContext) +369

[HttpException (0x80004005): A route named 'MS_attributerouteWebApi' is already in the route collection. Route names must be unique. Parameter name: name]
System.Web.HttpRuntime.FirstRequestInit(HttpContext context) +534
System.Web.HttpRuntime.EnsureFirstRequestInit(HttpContext context) +111 System.Web.HttpRuntime.ProcessRequestNotificationPrivate(IIS7WorkerRequest wr, HttpContext context) +718

Answer 1

To resolve this issue:

• Take a look whether you still have old dlls that you added custom routes with previously in your bin folder. If they are there, they are still therefore applied even though you have removed code. You need to remove them.
• Check also whether you have some old config files under App_Config folder left and not deleted. They could be also still applied. They need to be removed.