When methods have the name ...Async the exception "System.InvalidOperationException: No route matches the supplied values" occurs

Question

Steps to reproduce:

Create a new Web API project
Create a UsersController with the following code

.

[ApiController]
[Route("[controller]")]
public class UsersController : ControllerBase
{
    [HttpGet("{id:int}", Name = nameof(GetUserByIdAsync))]
    public async Task<ActionResult<object>> GetUserByIdAsync([FromRoute] int id)
    {
        object user = null;

        return Ok(user);
    }

    [HttpPost]
    public async Task<ActionResult<object>> CreateUserAsync()
    {
        object user = null;

        return CreatedAtAction(nameof(GetUserByIdAsync), new { id = 1 }, user);
    }
}

Call the url POST https://localhost:5001/users
You will get the exception

System.InvalidOperationException: No route matches the supplied values.

Rename both methods by removing the Async from the method names, the methods should look like

[HttpGet("{id:int}", Name = nameof(GetUserById))]
public async Task<ActionResult<object>> GetUserById([FromRoute] int id)
{
    // ...
}

[HttpPost]
public async Task<ActionResult<object>> CreateUser()
{
    // ...
}

Call the url POST https://localhost:5001/users again
You will receive an empty 201 response

So I'm assuming the error occurs with the method names, any ideas?

Fei Han · Accepted Answer · 2020-06-06 03:03:03Z

3

System.InvalidOperationException: No route matches the supplied values.

To fix above error, you can try to set SuppressAsyncSuffixInActionNames option to false, like below.

services.AddControllers(opt => { 
    opt.SuppressAsyncSuffixInActionNames = false; 
});

Or apply the [ActionName] attribute to preserve the original name.

[HttpGet("{id:int}", Name = nameof(GetUserByIdAsync))]
[ActionName("GetUserByIdAsync")]
public async Task<ActionResult<object>> GetUserByIdAsync([FromRoute] int id)
{

answered Jun 6, 2020 at 3:03

Fei Han

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3 Comments

Question3r Over a year ago

I would rather go for this opt.SuppressAsyncSuffixInActionNames = false; but what is the reason? And what are the disadvantages?

Question3r Over a year ago

It would be nice if you knew something about loss of features when setting the global bool

Fei Han Over a year ago

You can check this doc to know more about this change: learn.microsoft.com/en-us/dotnet/core/compatibility/…

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