hi
i have an asp core project with this config:

builder
    .Services.AddControllersWithViews()
    .AddMvcOptions(option =>
    {
        option.OutputFormatters.Clear();
        option.OutputFormatters.Add(
            new MessagePackOutputFormatter(ContractlessStandardResolver.Options)
        );
        option.InputFormatters.Clear();
        option.InputFormatters.Add(
            new MessagePackInputFormatter(ContractlessStandardResolver.Options)
        );
    });

i'm sending post data via a client formatted as msgpack, and include the 'Content-Type': 'application/x-msgpack' header
and it works fine, until i do
return NotFound() in my asp controller
which gives a warning in logs:

[12:22:46 WRN] No output formatter was found for content types '["application/problem+json", "application/problem+xml", "application/problem+json", "application/problem+xml", "application/problem+xml"]' to write the response.

and returns a 406 code instead of 404
samething when i return StatusCode()

but returning Created, Ok, and BadRequest works fine