几天前我问了一个类似的问题，但是我现在遇到了另一个控制器的问题，我一辈子都想不通为什么会返回404。
API控制器...

[Route("api/[controller]")]
[ApiController]
public class FilesController
{
    private readonly IFilesService _filesService;

    public FilesController(IFilesService filesService)
    {
        _filesService = filesService;
    }

    [HttpGet("{id}")]
    public IEnumerable<SupportFile> GetFiles(int id) {
        return _filesService.GetFiles(id);
    }

    [HttpGet("DownloadFile/{fileName}")]
    public async Task<FileStreamResult> DownloadFile(string fileName)
    {

        return await _filesService.DownloadFile(fileName);
    }
}

程序. cs ...

var builder = WebApplication.CreateBuilder(args);

// Add services to the container.
builder.Services.AddSingleton<DapperContext>();
builder.Services.AddScoped<IUserService, UserService>();
builder.Services.AddScoped<ISupportService, SupportService>();
builder.Services.AddScoped<IFilesService, FilesService>();
builder.Services.AddControllersWithViews();
builder.Services.AddControllers();

var app = builder.Build();

// Configure the HTTP request pipeline.
if (!app.Environment.IsDevelopment())
{
    // The default HSTS value is 30 days. You may want to change this for production scenarios, see https://aka.ms/aspnetcore-hsts.
    app.UseHsts();
}

app.UseHttpsRedirection();
app.UseStaticFiles();
app.MapControllers();
app.UseRouting();
app.MapDefaultControllerRoute();

app.MapFallbackToFile("index.html"); ;

app.Run();

代理.配置. js ...

const { env } = require('process');

const target = env.ASPNETCORE_HTTPS_PORT ? `https://localhost:${env.ASPNETCORE_HTTPS_PORT}` :
  env.ASPNETCORE_URLS ? env.ASPNETCORE_URLS.split(';')[0] : 'http://localhost:19229';

const PROXY_CONFIG = [
  {
    context: [
      "/api/*"
   ],
    target: target,
    secure: false,
    headers: {
      Connection: 'Keep-Alive'
    }
  }
]

module.exports = PROXY_CONFIG;

另一个工作正常的API控制器...

[Route("api/[controller]")]
[ApiController]
public class UsersController : ControllerBase
{

    private readonly IUserService _userService;

    public UsersController(IUserService userService)
    {
        _userService = userService;
    }

    [HttpPost]
    public User ModifyUser(AzureUser user)
    {
        return _userService.ModifyUser(user);
    }

    [HttpGet]
    public IEnumerable<User> GetUsers()
    {
        return _userService.GetUsers();
    }
}

但无论我做什么...
将返回一个404。
将返回一个404.
其他API控制器方法可以工作，因此端口正确。
其他的API控制器只有一个GET，每当我尝试使用属性路由添加多个GET时，它们都返回一个404。