how can i fix error 404 for dropzone in laravel

i want to make gallery for project with dropzone in laravel but i recieve error 404 .. often error 404 happen for wrong route but obviously every thing is right...

but i recieve this error

my form:

{

 < form action="" method="post" class="dropzone dz-clickable" id="myAwesomeDropzone">

}

my route:

Route::post('/admin/gallery/upload', 'admin\ProjectController@upload');

my function

 public function upload(Request $request ,$id){


    $files=$request->file('file');
    $name=rand()."-".$id.$files->getClientOriginalName();
    $files->move('upload/gallery/'.$id.'/',$name);
    $gallery=new Gallery();
    $gallery->product_id=$id;
    $gallery->url=$name;
    $gallery->save();

}

via Chebli Mohamed