ASP.NET CORE, Web API: No route matches the supplied values

I know this post is from 2017 but still i just faced the same problem and ended up here. And as it looks like you never found your mistake I'll write it here for anyone else that founds this post.

The problem is that when you call:

CreatedAtRoute("GetDocument", new { version = "1", controller = "Document", guid = doc.Guid.ToString("N")}, document);

You are telling the program to look for a "GetDocument" function that receives 3 parameters, in this case 3 strings but your actual "GetDocument" definition receives only 1 string that is your "guid":

[HttpGet("{guid}", Name = "GetDocument")]
public IActionResult GetByGuid(string guid)
{
    var doc = DocumentDataProvider.Find(guid);
    if (doc == null)
        return NotFound();

    return new ObjectResult(doc) {StatusCode = 200};
}

So for it to work you should have it like this:

CreatedAtRoute("GetDocument", new { guid = doc.Guid.ToString("N")}, document);

Another option would be to create a new get method with 3 strings and maybe you'll have to call it something different than "GetDocument".

Hope this helps the next one that comes looking for this :D

ASP.net core 3

Why this problem occurs:

"As part of addressing dotnet/aspnetcore#4849, ASP.NET Core MVC trims the suffix Async from action names by default. Starting with ASP.NET Core 3.0, this change affects both routing and link generation."

See more: https://docs.microsoft.com/en-us/dotnet/core/compatibility/aspnetcore#mvc-async-suffix-trimmed-from-controller-action-names

As @Chris Martinez says in this thread:

The reason for the change was not arbitrary; it addresses a different bug. If you're not affected by said bug and want to continue using the Async suffix as you had been doing.

How to solve

Re-enable it:

services.AddMvc(options =>
{
   options.SuppressAsyncSuffixInActionNames = false;
});

You should now pass the createActionName parameter including the Async suffix like this:

return CreatedAtAction("PostAsync", dto)

In my case it was a copy/paste error. The CreatedAtAction method had the wrong action name parameter. Make sure the first parameter (the actionName parameter) matches the action name (the function name). The corrected code is seen below: