خطای ۱۰۶۴ دیتابیس لاراول

درود دوستان...
خطای زیر:

   Illuminate\Database\QueryException  : SQLSTATE[42000]: Syntax error or access violation: 1064 You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version forthe right syntax to use near 'created_at) null, `updated_at` timestamp(created_at) null) default character set' at line 1 (SQL: create table `likes` (`id` int unsigned not null auto_increment primary key, `text` varchar(191) not null, `user_id` int unsigned not null, `likes_count` int not null default '0', `created_at` timestamp(created_at) null, `updated_at` timestamp(created_at) null) default characterset utf8mb4 collate 'utf8mb4_unicode_ci')

جدول دیتابیس زیر:

public function up()
    {
        Schema::create('likes', function (Blueprint $table) {
            $table -> increments('id');
            $table -> string('text');
            $table -> unsignedInteger('user_id');
            $table -> integer('likes_count') -> default(0);
            $table -> timestamps('created_at');

            $table -> foreign('user_id') -> references('id') -> on('users');
        });
    }