🇵🇹Portugal @LuisPimentelLopes

#5 also worked for me. Thank you @ericdsd

Previous patches didn't work with 10.3, adding a compatible patch.

Hi, I also installed Storybook with Drupal integration with the reproduction steps and got the same issue but on the 2.0.0-alpha1.

After a quick debug, it seems the controller is trying to create an instance of a plugin that doesn't exists.

  /**
   * Creates an instance.
   *
   * @throws \Drupal\sdc\Exception\ComponentNotFoundException
   *
   * @internal
   */
  public function createInstance($plugin_id, array $configuration = []): Component {
    $configuration['app_root'] = $this->appRoot;
    $configuration['enforce_schemas'] = $this->shouldEnforceSchemas(
      $this->definitions[$plugin_id] ?? []
    );
    try {
      $instance = parent::createInstance($plugin_id, $configuration);
      if (!$instance instanceof Component) {
        throw new ComponentNotFoundException(sprintf(
          'Unable to find component "%s" in the component repository.',
          $plugin_id,
        ));
      }
      return $instance;
    }
    catch (PluginException $e) {
      // Cast the PluginNotFound to a more specific exception.
      $message = sprintf(
        'Unable to find component "%s" in the component repository. [%s]',
        $plugin_id,
        $e->getMessage()
      );
      throw new ComponentNotFoundException($message, $e->getCode(), $e);
    }
  }