用 Laravel-cors 做跨域上传图片出现 404

A站为请求站http://a.aa.com/
B站为接口站http://a.bb.com/api/
用的API无状态路由，

Route::middleware(['cross'])->group(function ($router) {
         $router->post('uploadImgFile', 'FileController@uploadImgAudioFile'); //上传图片
    });

中间件

'cross'=>\Barryvdh\Cors\HandleCors::class,

配置是默认的

'supportsCredentials' => false,
    'allowedOrigins' => ['*'],
    'allowedHeaders' => ['*'],
    'allowedMethods' => ['*'], // ex: ['GET', 'POST', 'PUT',  'DELETE']
    'exposedHeaders' => [],
    'maxAge' => 0,

A站前端代码

var blob = item.getAsFile(),
            reader = new FileReader();
          var formData = new FormData();
          var name = encodeURIComponent('img-' + new Date().getTime() + '.png');
          formData.append('upload', blob, name);

          $.ajax({
            url: 'http://a.bb.com/api/uploadImgFile',//这是我测试的本地域名
            type: 'POST',
            data: formData,            
            //这两个设置项必填
            contentType: false,
            processData: false,
            success: function (res) {
              console.log(res);              
              if (res.code == 0) {
              }
            }
          });

提示的错误

POST http://a.bb.com/api/uploadImgFile 404 (Not Found)
Access to XMLHttpRequest at 'http://a.bb.com/api/uploadImgFile' from origin 'http://a.aa.com' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource.

我是哪里配置出错了吗？