How to solve the error Route is not bound in laravel 5.1?

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when runnig my view it shows the Route is not bound error.

following is my controller code public function assignRoles() {

    $title = trans('admin/privilegeduser.assign_roles');

    $routes = collect(Route::getRoutes()->getRoutes());

    $admin_routes = $routes->filter( function ($route) {

        if (array_has($route->getAction(), 'controller')) {

            $controller_action = array_get($route->getAction(), 

'controller');

            $is_admin_route = preg_match('/App\\\\Http\\\\Controllers\\\\Admin\\\\.*/', 
                $controller_action);

            return (is_numeric($is_admin_route) && ($is_admin_route > 0));

        }

        return false;

    }); 

    // dd($admin_routes);

    return view('app.admin.privilegeduser.assign_roles',compact('title','admin_routes'));

}

following is the view code

@extends('app.admin.layouts.default')

@section('title') } :: @parent @stop

@section('styles')

@endsection

@section('main')

                <div class="panel panel-success" data-sortable-id="ui-widget-11">
                    <div class="panel-heading">
                        <div class="panel-heading-btn">
                            <a href="javascript:;" class="btn btn-xs btn-icon btn-circle btn-default" data-click="panel-expand"><i class="fa fa-expand"></i></a>
                            <a href="javascript:;" class="btn btn-xs btn-icon btn-circle btn-success" data-click="panel-reload"><i class="fa fa-repeat"></i></a>
                            <a href="javascript:;" class="btn btn-xs btn-icon btn-circle btn-warning" data-click="panel-collapse"><i class="fa fa-minus"></i></a>
                            <a href="javascript:;" class="btn btn-xs btn-icon btn-circle btn-danger" data-click="panel-remove"><i class="fa fa-times"></i></a>
                        </div>
                        <h4 class="panel-title">  </h4> 
                    </div>
                    <div class="panel-body"> 
                      @include('utils.errors.list')
                      @include('flash::message')

                    <form action="" method="post">
                        <input type="hidden" name="_token" value="">
                            <div class="form-group">
                                <label class="control-label col-md-4 col-sm-4"> </label>
                                    <div class="col-md-6 col-sm-6">
                                        <a href="{!! url('admin/assign_role') !!}"><div id="new" class="btn btn-primary"></div></a>
                                    </div>
                                </div>
                                <div class="routes">
                                    @foreach ($admin_routes as $value)

                                    <input type="checkbox" name="admin_routes">

                                    @endforeach
                                </div>
                                <div class="btn col-sm-offset-4">
                                    <button type="submit" class="btn btn-primary"></button>
                            </div>
                        </form>
                    </div>
                </div>

@endsection

@section('scripts') @parent

<script>
    $(document).ready(function() {
        App.init();           
    });



</script>
@endsection

via Chebli Mohamed