InvalidArgumentException... Class not Found in Custom Module

Question

Here is the simplified error:

InvalidArgumentException: Class "\Drupal\prepcart\Controller\PrepCartController" does not exist. in Drupal\Core\DependencyInjection\ClassResolver->getInstanceFromDefinition() (line 24 of core/lib/Drupal/Core/DependencyInjection/ClassResolver.php).

Full Stack Trace:

The website encountered an unexpected error. Please try again later. InvalidArgumentException: Class "\Drupal\prepcart\Controller\PrepCartController" does not exist. in Drupal\Core\DependencyInjection\ClassResolver->getInstanceFromDefinition() (line 24 of core/lib/Drupal/Core/DependencyInjection/ClassResolver.php). Drupal\Core\Controller\ControllerResolver->createController('\Drupal\prepcart\Controller\PrepCartController::content') (Line: 74) Drupal\Core\Controller\ControllerResolver->getControllerFromDefinition('\Drupal\prepcart\Controller\PrepCartController::content', '/cart') (Line: 91) Drupal\Core\Controller\ControllerResolver->getController(Object) (Line: 132) Symfony\Component\HttpKernel\HttpKernel->handleRaw(Object, 1) (Line: 64) Symfony\Component\HttpKernel\HttpKernel->handle(Object, 1, 1) (Line: 57) Drupal\Core\StackMiddleware\Session->handle(Object, 1, 1) (Line: 47) Drupal\Core\StackMiddleware\KernelPreHandle->handle(Object, 1, 1) (Line: 98) Drupal\page_cache\StackMiddleware\PageCache->pass(Object, 1, 1) (Line: 77) Drupal\page_cache\StackMiddleware\PageCache->handle(Object, 1, 1) (Line: 47) Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle(Object, 1, 1) (Line: 50) Drupal\Core\StackMiddleware\NegotiationMiddleware->handle(Object, 1, 1) (Line: 23) Stack\StackedHttpKernel->handle(Object, 1, 1) (Line: 628) Drupal\Core\DrupalKernel->handle(Object) (Line: 19)

Relevant information: Drupal Core 8.1.8 (I know 8.2 is out but this shouldn't matter I believe - we are pinned to this version due to Lightning)

And here is the relevant files involved:

PrepCartController.php

<?php
/**
 * @file
 * Contains \Drupal\prepcart\Controller\PrepCartController.
 */
namespace Drupal\prepcart\Controller;
use Drupal\Core\Controller\ControllerBase;
class PrepCartController extends ControllerBase {
  public function content() {
    return array(
      '#type' => 'markup',
      '#markup' => $this->t('Hello, IHM!'),
    );
  }
};

To make life easier this is the directory structure:

drwxr-xr-x   170B Oct 18 07:05 ./
-rw-r--r--   222B Oct 18 06:36 ./prepcart.info.yml
-rw-r--r--   195B Oct 18 07:05 ./prepcart.routing.yml
drwxr-xr-x   102B Oct 18 06:53 ./src/
drwxr-xr-x   102B Oct 18 06:54 ./src/Controller/
-rw-r--r--   349B Oct 18 06:54 ./src/Controller/PrepCartController.php

For some reason the module won't show on the modules page but I can interact with it fine on the CLI using drush?

Trust me when I say I have been ALL over Google and Stack for this. Major love to whomever can help me here.

Answer 1

I had the same problem once, clearing caches from drush was not sufficient. I cleared them from the drupal interface and the error message was gone...

Answer 2

I am facing Similar Kind of Issue once at drupal 10

My code:

Routing File:

learning.learningpage:
  path: "myworld"
  defaults:
    _controller: 'Drupal\learning\Controller\MyLearningWorldController::showData'
    _title: "This is my learning World"
  requirements:
    _permission: "content access"

Controller:

<?php
namespace Drupal\learning\Controller;
use Drupal\Core\Controller\ControllerBase;

class MyLearningWorldController extends ControllerBase{

    public function showData(){
        return [
            '#markup' => 'Enter My learning World'
        ];
    }
}

I got error :

InvalidArgumentException: Class "Drupal\learning\Controller\MyLearningWorldController" does not exist. in Drupal\Core\DependencyInjection\ClassResolver->getInstanceFromDefinition() (line 24 of C:\xampp\htdocs\d10\web\core\lib\Drupal\Core\DependencyInjection\ClassResolver.php).

I have clear cache using Drush , but error still not solved.

After that I have clear cache from admin panel (admin/config/development/performance). Then issue solved for me.