I can't get the routing by api version to work (web api, old style asp startup class)

[ofirgeller]

I'm following the basic web api example but getting an AmbiguousMatchException when making a request.

Since the example is for the new top level asp setup and I have the older startup + program file setup I had to adapt a bit,

            services.AddApiVersioning(options =>
                {
                    options.DefaultApiVersion = new ApiVersion(1);
                    options.ReportApiVersions = true;
                    options.AssumeDefaultVersionWhenUnspecified = true;
                    options.ApiVersionReader = ApiVersionReader.Combine(
                        new UrlSegmentApiVersionReader(),
                        new HeaderApiVersionReader("X-Api-Version"),
                        new QueryStringApiVersionReader());
                }).AddMvc();

inside ConfigureServices.

any ideas on what I might be doing wrong?

[bh4ks]

Spent hrs trying to solve similar issue. I used the old deprecated version and that sorted the issue. No expert but must be the new version.

[commonsensesoftware]

Do you have an example or repro of a controller that produces this error?

[commonsensesoftware]

@ofirgeller Much apologies! I'm just seeing this discussion and realized I've never replied. 😞 No donut for me.

The 2 most common scenarios that can produce this are:

1. Forgetting IApiVersioningBuilder.AddMvc()
   • This is different from the old version because that's how controllers and Minimal APIs are separated
   • AddMvc does not add the whole MVC stack and is different from IServiceCollection.AddMvc; only MVC (Core) is added
   • You have this, so that shouldn't be the problem
2. Not applying [ApiController]
   • This is the required convention to signal a controller is an API controller (versus a UI controller if you have both)
   • You can apply it directly on a controller
   • You can also apply it to all controllers a la: [assembly: ApiController]
   • If you don't use the API Behaviors, then you need to a custom IApiControllerSpecification so API Versioning picks it up
     • I won't elaborate further until you confirm you're in that position. I don't want you to go down a 🐰 🕳️

[bh4ks]

See link below. <https://github.com/bh4ks/Towns> [Towns.png] bh4ks/Towns<https://github.com/bh4ks/Towns> github.com<https://github.com/bh4ks/Towns> If you used v1 or v2 on url it replicates error. On 9 Oct 2024, at 23:05, Chris Martinez ***@***.***> wrote:  Do you have an example or repro of a controller that produces this error? — Reply to this email directly, view it on GitHub<#1107 (reply in thread)>, or unsubscribe<https://github.com/notifications/unsubscribe-auth/AECPHIDND4R5URPR37RDITTZ2WSDVAVCNFSM6AAAAABNNZVD5CVHI2DSMVQWIX3LMV43URDJONRXK43TNFXW4Q3PNVWWK3TUHMYTAOBZG42TMMA>. You are receiving this because you commented.Message ID: ***@***.***>

[commonsensesoftware]

As mentioned above, I'm 99% sure this is happening in your case because you do not have a call to .AddMvc() here. IServiceCollection.AddApiVersioning only adds the barebones services for use with Minimal APIs. AddApiVersioning returns a IApiVersioningBuilder, which can be used to chain further configuration options. Under the hood, IApiVersioningBuilder.AddMvc will call through to IServiceCollection.AddMvcCore. Hopefully that works for you and gets you on your way.

Minimal APIs were not introduced until .NET 6. The last supported version in the old libraries were .NET 5, which is why you didn't see this problem nor have to configure it otherwise. The migration guide has more information that you may find useful.