php - Resource error when I submmit laravel form with html in request

one text

I get 403 error when I submit a form with html in in request body

I want to implement a newsletter in my Laravel site, I have used grapesjs library. In create page I design newsletter and then I want to send html from this blade to next blade using forrm. But when I append that in request it gives 403 error on server, although this works on local machine. Bellow is my script

Form

<form action="{{ route('admin.newsletters.preview') }}" method="POST">
    @csrf
    <div class="form-group">
        <label class="required">Title</label>
        <input type="text" name="title" class="form-control" placeholder="Title" required>
    </div>
    <input type="hidden" name="newsletter">
    <div id="gjs"></div>
    <button class="btn btn-success mt-3">Preview & Send</button>
</form>

Script

<script src="https://unpkg.com/grapesjs"></script>
<script src="https://unpkg.com/grapesjs-preset-newsletter"></script>

<script type="text/javascript">
    var editor = grapesjs.init({
        container: '#gjs'
        , plugins: ['gjs-preset-newsletter']
        , pluginsOpts: {
            'gjs-preset-newsletter': {
                modalTitleImport: 'Import template',
                // ... other options
            }
        }
        , storageManager: {
            type: null
        }
    , });

    $("form").submit(function(eventObj) {
        var form = $(this);
        // var newsletter = editor.getHtml();
        var newsletter = editor.runCommand('gjs-get-inlined-html');
        form.find('input[name="newsletter"]').val(newsletter);
        return true;
    });

</script>

Source