Describe the bug

The OPTIONS pre-flight request issued by the browser is handled with a "405 Method not allowed" response.

To Reproduce

public class Startup
{
	public Startup(IConfiguration configuration)
	{
		Configuration = configuration;
	}

	public IConfiguration Configuration { get; }

	public void ConfigureServices(IServiceCollection services)
	{

		services.AddControllers();
		services.AddCors();
	}

	public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
	{

		if (env.IsDevelopment())
		{
			app.UseDeveloperExceptionPage();
		}

		app.UseHttpsRedirection();

		app.UseRouting();
		
		app.UseCors();
		
		app.UseAuthorization();

		app.UseEndpoints(endpoints =>
		{

			endpoints.MapControllers().RequireCors(builder =>
			{
				builder
				.WithOrigins("http://localhost:4200")
				.AllowAnyHeader()
				.AllowCredentials()
				.AllowAnyMethod();
			});
		});
	}
}

I tried issuing an OPTIONS request with PostMan and it also fails with a 405 response.

If I explicitly add a method with a matching route in my controller to handle the OPTIONS request as follows, then the CORS middleware works just fine.

 [HttpOptions("{id}")]
public void DoNothing(string id)
{
}

Note: The controller method does not actually get called so the mere existence of the route is enough.

I hope this was useful.

Log output

info: Microsoft.AspNetCore.Hosting.Diagnostics[1]
Request starting HTTP/2 OPTIONS https://localhost:5001/api/tags/833a45a7550b441e8f222b6fccf70aaa
info: Microsoft.AspNetCore.Cors.Infrastructure.CorsMiddleware[10]
No CORS policy found for the specified request.
info: Microsoft.AspNetCore.Routing.EndpointMiddleware[0]
Executing endpoint '405 HTTP Method Not Supported'
info: Microsoft.AspNetCore.Routing.EndpointMiddleware[1]
Executed endpoint '405 HTTP Method Not Supported'
info: Microsoft.AspNetCore.Hosting.Diagnostics[2]
Request finished in 13.084900000000001ms 405

Further technical details

• ASP.NET Core version
  ASP.NET Core 3.0

• Include the output of dotnet --info
  dotnet --info
  .NET Core SDK (reflecting any global.json):
  Version: 3.0.100
  Commit: 04339c3a26

Runtime Environment:
OS Name: Windows
OS Version: 10.0.18362
OS Platform: Windows
RID: win10-x64
Base Path: C:\Program Files\dotnet\sdk\3.0.100\

Host (useful for support):
Version: 3.0.0
Commit: 7d57652f33

.NET Core SDKs installed:
2.0.2 [C:\Program Files\dotnet\sdk]
2.1.1-preview-007094 [C:\Program Files\dotnet\sdk]
2.1.1-preview-007118 [C:\Program Files\dotnet\sdk]
2.1.1-preview-007165 [C:\Program Files\dotnet\sdk]
2.1.4 [C:\Program Files\dotnet\sdk]
2.1.100-preview-007326 [C:\Program Files\dotnet\sdk]
2.1.100-preview-007354 [C:\Program Files\dotnet\sdk]
2.1.100-preview-007363 [C:\Program Files\dotnet\sdk]
2.1.100 [C:\Program Files\dotnet\sdk]
2.1.200-preview-007474 [C:\Program Files\dotnet\sdk]
2.1.200-preview-007517 [C:\Program Files\dotnet\sdk]
2.1.200-preview-007576 [C:\Program Files\dotnet\sdk]
2.1.200 [C:\Program Files\dotnet\sdk]
2.1.202 [C:\Program Files\dotnet\sdk]
2.1.300-rc1-008673 [C:\Program Files\dotnet\sdk]
2.1.400-preview-009171 [C:\Program Files\dotnet\sdk]
2.1.400 [C:\Program Files\dotnet\sdk]
2.1.500-preview-009297 [C:\Program Files\dotnet\sdk]
2.1.500-preview-009335 [C:\Program Files\dotnet\sdk]
2.1.500-preview-009404 [C:\Program Files\dotnet\sdk]
2.1.500 [C:\Program Files\dotnet\sdk]
2.1.502 [C:\Program Files\dotnet\sdk]
2.1.503 [C:\Program Files\dotnet\sdk]
2.1.600-preview-009426 [C:\Program Files\dotnet\sdk]
2.1.600-preview-009472 [C:\Program Files\dotnet\sdk]
2.1.600-preview-009497 [C:\Program Files\dotnet\sdk]
2.1.700-preview-009601 [C:\Program Files\dotnet\sdk]
2.1.800-preview-009696 [C:\Program Files\dotnet\sdk]
2.1.801 [C:\Program Files\dotnet\sdk]
2.2.100 [C:\Program Files\dotnet\sdk]
3.0.100-preview5-011568 [C:\Program Files\dotnet\sdk]
3.0.100 [C:\Program Files\dotnet\sdk]

.NET Core runtimes installed:
Microsoft.AspNetCore.All 2.1.0-rc1-final [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
Microsoft.AspNetCore.All 2.1.2 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
Microsoft.AspNetCore.All 2.1.3 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
Microsoft.AspNetCore.All 2.1.5 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
Microsoft.AspNetCore.All 2.1.6 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
Microsoft.AspNetCore.All 2.1.7 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
Microsoft.AspNetCore.All 2.1.9 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
Microsoft.AspNetCore.All 2.1.11 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
Microsoft.AspNetCore.All 2.1.12 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
Microsoft.AspNetCore.All 2.1.13 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
Microsoft.AspNetCore.All 2.2.0 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.All]
Microsoft.AspNetCore.App 2.1.0-rc1-final [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 2.1.2 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 2.1.3 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 2.1.5 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 2.1.6 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 2.1.7 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 2.1.9 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 2.1.11 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 2.1.12 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 2.1.13 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 2.2.0 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 3.0.0-preview5-19227-01 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 3.0.0 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
Microsoft.NETCore.App 2.0.0 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 2.0.3 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 2.0.5 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 2.0.6 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 2.0.7 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 2.0.9 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 2.1.0-rc1 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 2.1.2 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 2.1.3 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 2.1.5 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 2.1.6 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 2.1.7 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 2.1.9 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 2.1.11 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 2.1.12 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 2.1.13 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 2.2.0 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 3.0.0-preview5-27626-15 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.NETCore.App 3.0.0 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
Microsoft.WindowsDesktop.App 3.0.0-preview5-27626-15 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
Microsoft.WindowsDesktop.App 3.0.0 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]

• The IDE (VS / VS Code/ VS4Mac) you're running on, and it's version
  Microsoft Visual Studio Community 2019
  Version 16.3.10
  VisualStudio.16.Release/16.3.10+29519.87
  Microsoft .NET Framework
  Version 4.8.03752