cover image must be an image in laravel 8

Question

Im new with laravel 8, I have been trying uploading a form with a file field but I keep getting an error image must be an image even though I have enctype='multipart/form-data' included in a form. I real need your help.

Blade Template

 @extends('layouts.app')
  @section('contents')
   <div class="container">
     <h1> Create a Posts</h1>
       {!! Form::open(['action' =>['App\Http\Controllers\PostController@store','enctype'=>'multipart/form-data', 'method'=>'POST']]) !!}
      <div class="form-group">
         {{Form::label('title', 'Title')}}
         {{Form::text('title','',['class'=>'form-control','placeholder'=>'Title'])}}
      </div>
     <div class="form-group">
        {{Form::label('body', 'Body')}}
        {{Form::textarea('body','',['class'=>'form-control','id'=>'article-ckeditor','placeholder'=>'Bodytext'])}}
    </div>
    <br>
    <div class="form-group">
        <div class="image">
       {{Form::file('cover_image')}}
        </div>
    </div>
    <br>
    {{Form::submit('Submit',['class'=>'btn btn-primary']);}}
    {!! Form::close() !!}


   
</div>
@endsection

Controller

 <?php
   namespace App\Http\Controllers;

   use Illuminate\Http\Request;
   use App\Models\Post;
   use App\Models\User;
 public function store(Request $request)
    {
        $validatedData = $request->validate([
            'title' => ['required', 'unique:posts', 'max:500000'],
            'body' => ['required'],
            'cover_image'=>['image','nullable','max:19999']
        ]);
        //handle file uploads
        if($request->hasfile('cover_image')){
           return '123';
            


        }
    }

routes Route::resource('/post', PostController::class);