NotFoundHttpException in RouteCollection.php line 161 While Updating Data in Laravel 5.3

Question

I got the error when i want to update a data
So when i click the submit button, the error happens
I'm using the same form to update and input data

This is the app/Http/Controllers/PKController.php at edit function part

  public function edit($id)
{
  $data['result'] = \App\PKerja::where('id_dokumen', $id)->first();
  return view('pkerja/form')->with($data);
}

public function update(Request $request, $id)
{
  $rules = [
    'nm_dokumen'    => 'required|max:40',
    'no_dokumen'    => 'required|max:40',
    'pj_dokumen'    => 'required|max:40',
    'mh_dokumen'    => 'required|max:50',
    'tt_dokumen'    => 'required',
    'jw_dokumen'    => 'required|max:10',
    'st_dokumen'    => 'required'
  ];
  $this->validate($request, $rules);

  $input = $request->all();
  $result = \App\PKerja::where('id_dokumen', $id)->first();
  $status = $result->update($input);

  if ($status) return redirect('/')->with('success', 'Data berhasil 
  diubah');
  else return redirect('/')->with('error', 'Data gagal diubah');
}

And this is the routes/web.php

Route::get('/', 'PKController@index');

Route::get('/', 'PKController@index');
Route::get('pkerja/add', 'PKController@create');
Route::post('pkerja/add', 'PKController@store');

Route::get('pkerja/{id}/edit', 'PKController@edit');
Route::patch('pkerja/{id}/edit', 'PKController@update');
Route::delete('pkerja/{id}/delete', 'PKController@destroy');