Route [admin.index] not defined

working with Laravel 5.8 and I have following href link,

href=""

and my web.php route is like this,

Route::get('/admin.index', function () {
    return view('admin.index')->name('admin.index');
});

but I got following error message here Route [admin.index] not defined. (View: F:\2020 technologies\laravel\bestbrandtoday\resources\views\_includes\nav\admin.blade.php)

how could I fix this problem?

via Chebli Mohamed