logError example

public function validate() {
    if (!$this->validated) {
      $this->errors = [];
      // Create the list of installs and uninstalls.       $this->createExtensionChangelist();
      // Validate renames.       foreach ($this->getUnprocessedConfiguration('rename') as $name) {
        $names = $this->storageComparer->extractRenameNames($name);
        $old_entity_type_id = $this->configManager->getEntityTypeIdByName($names['old_name']);
        $new_entity_type_id = $this->configManager->getEntityTypeIdByName($names['new_name']);
        if ($old_entity_type_id != $new_entity_type_id) {
          $this->logError($this->t('Entity type mismatch on rename. @old_type not equal to @new_type for existing configuration @old_name and staged configuration @new_name.', ['@old_type' => $old_entity_type_id, '@new_type' => $new_entity_type_id, '@old_name' => $names['old_name'], '@new_name' => $names['new_name']]));
        }
        // Has to be a configuration entity.         if (!$old_entity_type_id) {
          $this->logError($this->t('Rename operation for simple configuration. Existing configuration @old_name and staged configuration @new_name.', ['@old_name' => $names['old_name'], '@new_name' => $names['new_name']]));
        }
      }
      $this->eventDispatcher->dispatch(new ConfigImporterEvent($this), ConfigEvents::IMPORT_VALIDATE);
      if (count($this->getErrors())) {
        $errors = array_merge(['There were errors validating the config synchronization.'], $this->getErrors());
        throw new ConfigImporterException(implode(PHP_EOL, $errors));
      }
      

/** * Validates the configuration to be imported. * * @param \Drupal\Core\Config\ConfigImporterEvent $event * The Event to process. * * @throws \Drupal\Core\Config\ConfigNameException */
  public function onConfigImporterValidate(ConfigImporterEvent $event) {
    if ($this->state->get('config_import_test.config_import_validate_fail', FALSE)) {
      // Log more than one error to test multiple validation errors.       $event->getConfigImporter()->logError('Config import validate error 1.');
      $event->getConfigImporter()->logError('Config import validate error 2.');
    }
  }

  /** * Handles the missing content event. * * @param \Drupal\Core\Config\Importer\MissingContentEvent $event * The missing content event. */
  public function onConfigImporterMissingContentOne(MissingContentEvent $event) {
    

$this->logger->notice(sprintf('Migration "%s" does not exists. Ignoring it', $migration));

                continue;
            }

            /** @var MigrationStep $migration */
            $migration = new $migration();

            try {
                $migration->update($this->connection);
            } catch (\Exception $e) {
                $this->logError($migration, $e->getMessage());

                $this->enrichException($e);

                throw $e;
            }

            $this->setExecuted($migration);
            yield $migration::class;
        }
    }

    

  public function onConfigImporterValidate(ConfigImporterEvent $event) {
    foreach (['delete', 'create', 'update'] as $op) {
      foreach ($event->getConfigImporter()->getUnprocessedConfiguration($op) as $name) {
        try {
          Config::validateName($name);
        }
        catch (ConfigNameException $e) {
          $message = $this->t('The config name @config_name is invalid.', ['@config_name' => $name]);
          $event->getConfigImporter()->logError($message);
        }
      }
    }
    $config_importer = $event->getConfigImporter();
    if ($config_importer->getStorageComparer()->getSourceStorage()->exists('core.extension')) {
      $this->validateModules($config_importer);
      $this->validateThemes($config_importer);
      $this->validateDependencies($config_importer);
    }
    else {
      $config_importer->logError($this->t('The core.extension configuration does not exist.'));
    }

  public function onConfigImporterValidateNotEmpty(ConfigImporterEvent $event) {
    $importList = $event->getConfigImporter()->getStorageComparer()->getSourceStorage()->listAll();
    if (empty($importList)) {
      $event->getConfigImporter()->logError($this->t('This import is empty and if applied would delete all of your configuration, so has been rejected.'));
      $event->stopPropagation();
    }
  }

  /** * Checks that the configuration synchronization is valid. * * This event listener checks that the system.site:uuid's in the source and * target match. * * @param \Drupal\Core\Config\ConfigImporterEvent $event * The config import event. */

->getStorageComparer()
              ->getSourceStorage()
              ->read($unprocessed_configuration);
            $workflow_config = $event->getConfigImporter()
              ->getStorageComparer()
              ->getTargetStorage()
              ->read($unprocessed_configuration);
            $diff = array_diff_key($workflow_config['type_settings']['states'], $original_workflow_config['type_settings']['states']);
            foreach (array_keys($diff) as $state_id) {
              $state = $workflow->getTypePlugin()->getState($state_id);
              if ($workflow->getTypePlugin()->workflowStateHasData($workflow, $state)) {
                $event->getConfigImporter()->logError($this->t('The moderation state @state_label is being used, but is not in the source storage.', ['@state_label' => $state->label()]));
              }
            }
          }
          if ($op === 'delete') {
            if ($workflow->getTypePlugin()->workflowHasData($workflow)) {
              $event->getConfigImporter()->logError($this->t('The workflow @workflow_label is being used, and cannot be deleted.', ['@workflow_label' => $workflow->label()]));
            }
          }
        }
      }
    }
  }

        if ($bundle_of = $entity_type->getBundleOf()) {
          // Work out if there are entities with this bundle.           $bundle_of_entity_type = $this->entityTypeManager->getDefinition($bundle_of);
          $bundle_id = ConfigEntityStorage::getIDFromConfigName($config_name, $entity_type->getConfigPrefix());
          $entity_query = $this->entityTypeManager->getStorage($bundle_of)->getQuery();
          $entity_ids = $entity_query->condition($bundle_of_entity_type->getKey('bundle'), $bundle_id)
            ->accessCheck(FALSE)
            ->range(0, 1)
            ->execute();
          if (!empty($entity_ids)) {
            $entity = $this->entityTypeManager->getStorage($entity_type_id)->load($bundle_id);
            $event->getConfigImporter()->logError($this->t('Entities exist of type %entity_type and %bundle_label %bundle. These entities need to be deleted before importing.', ['%entity_type' => $bundle_of_entity_type->getLabel(), '%bundle_label' => $bundle_of_entity_type->getBundleLabel(), '%bundle' => $entity->label()]));
          }
        }
      }
    }
  }

}

  public function onConfigImporterValidate(ConfigImporterEvent $event) {
    // Make sure config syncs performed via the Config UI don't break, but     // don't worry about syncs initiated via the command line.     if (PHP_SAPI === 'cli') {
      return;
    }
    $importer = $event->getConfigImporter();
    $core_extension = $importer->getStorageComparer()->getSourceStorage()->read('core.extension');
    if (!isset($core_extension['module']['config'])) {
      $importer->logError($this->t('Can not uninstall the Configuration module as part of a configuration synchronization through the user interface.'));
    }
  }

  /** * {@inheritdoc} */
  public static function getSubscribedEvents(): array {
    $events[ConfigEvents::IMPORT_VALIDATE][] = ['onConfigImporterValidate', 20];
    return $events;
  }

}