Can't upload file to Laravel 8?

Question

Laravel

I can't upload the file to the server, what's the problem?

Sending

if ($request->isMethod('post') && $request->file('file')) {

            $file = $request->file('file');
            $upload_folder = 'public/folder';
            $filename = $file->getClientOriginalName(); // 
    
            Storage::putFileAs($upload_folder, $file, $filename);
    
        }
        return $request;

<form action="/ajax/add" method="POST" enctype="multipart/form-data" class="block-add-new-exercise">
            @csrf 
            <div class="block">
                <label>Имя задачи:</label>
                <input name="name" type="text" placeholder="Введите значение">
            </div>
            <div class="block">
                <label>Описание:</label>
                <input name="description" type="text" placeholder="Введите значение">
            </div>
            <div class="block">
                <label>До какой даты выполнить:</label>
                <input name="date" type="date" placeholder="Введите значение">
            </div>
            <div class="block">
                <label>Введите хэштеги (через запятую):</label>
                <div name="hashtag" id="hashtags" type="text" placeholder="Введите значение" contenteditable="true"></div>
            </div>
            <div class="block">
                <label>Укажите приоритет (от 1 до 10 - чем меньше тем приоритетние):</label>
                <input name="priority" type="number" placeholder="Введите значение">
            </div>
            <div class="block" style="margin-bottom: 22px;">
                <label>Прикрепить файл:</label>
                <input name="file" type="file">
            </div>

            <div class="block">
                <button type="submit" id="submit">Добавить</button>
                <button id="cancel">Отмена</button>
            </div>
        </form>

I receive

{"_token":"hTTrrf6jTFeqUPHvFlhMUmgZtFWRHmcM5u7Ouo4m","name":"123","description":"123","date":"0132-03-12","priority":"12","file":{}}