1. 报错 Disk [admin] not configured, please add a disk config in `config/filesystems.php`.

在config/filesystem.php的disks项中添加如下内容：

'admin' => [
    'driver' => 'local',
    'root' => public_path('upload'),
    'visibility' => 'public',
    'url' => env('APP_URL').'/public/upload/',
],
2. Unable to guess the mime type as no guessers are available (Did you enable the php_fileinfo extension
原因是php没有开启php_fileinfo扩展，在php.ini中开启扩展即可
3. 图片上传之后不显示的问题
修改config/admin.php中的upload项，修改为：

'upload' => [

    // Disk in `config/filesystem.php`.
    'disk' => 'public',  //该项值原为admin,修改为public

    // Image and file upload path under the disk above.
    'directory' => [
        'image' => 'images',
        'file'  => 'files',
    ],
],