summernote.blade.php

<div class="form-group">
            <textarea name="summernoteInput" id="summernote" class="summernote"></textarea>
            <script>
            $(document).ready(function() {
                //initialize summernote
                $('#summernote').summernote({
                    lang: 'pt-BR',
                    height: 300,                 
                    toolbar: [
                    // [groupName, [list of button]]
                    ['style', ['bold', 'italic', 'underline', 'clear']],
                    ['font', ['strikethrough', 'superscript', 'subscript']],
                    ['fontsize', ['fontsize']],
                    ['fontname', ['fontname']],
                    ['color', ['color']],
                    ['para', ['ul', 'ol', 'paragraph']],
                    ['height', ['height']],
                    ['picture', ['picture']],
                    ['link', ['link']],
                    ['video', ['video']],
                    ['hr', ['hr']],        
                    ],                                   
                });                 
                //set the content to summernote using `code` attribute.               
                $('.summernote').summernote('code', content);
            });
        </script>
        </div>

$('.summernote').summernote('code', content); in this line How are you getting the content?. I'm sorry I can't see where you have initialized the content variable.