codeigniter: route cannot be found while reverse-routing.

Hi… i get the error mentioned in the title when i try to update a row in db. And the validation failes.

Routes.php In a group admin

//Kategorier
	$routes->get('cat/list', 'CatController::index');
	$routes->get('cat/create', 'CatController::create');
	$routes->post('cat/store', 'CatController::store');
	$routes->get('cat/edit/(:num)', 'CatController::edit/$1');
	$routes->post('cat/update/(:num)', 'CatController::update/$1');
	$routes->get('cat/delete/(:num)', 'CatController::delete/$1');

in the controller

 ## Validation
		  $input = $this->validate([
			'kategori' => 'required|min_length[3]',
		  ]);
  
		  if (!$input) {
			 return redirect()->route('admin/cat/edit/'.$id)->withInput()->with('validation',$this->validator); 
		  } else {

error message from debug bar

          ## Validation
83           $input = $this->validate([
84             'kategori' => 'required|min_length[3]',
85           ]);
86   
87           if (!$input) {
88              return redirect()->route('admin/cat/edit/'.$id)->withInput()->with('validation',$this->validator); 
89           } else {

With line 88 marked.

Is there enough info to answer?

Rgrds Bengt