InvalidArgumentException: Class ... does not exist in custom configuration form

I create configuration form, so that I could dynamically set the API key for my custom weather module.

But when I write in the url address http://drupalsite/admin/config/services/weather/settings I get the error:

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

I checked the Class Name and File name and cleared the caches but the error did not go away. How to fix it?

weather.routing.yml

weather.weather_page:                               
  path: '/weather/{city}'
  defaults:                                                       
    _controller: '\Drupal\weather\Controller\WeatherPage::getWeather'                          
  requirements:                                        
     _permission: 'access content'
weather.settings:
  path: '/admin/config/services/weather/settings'
  defaults:
    _form: '\Drupal\weather\Form\WeatherSettingsForm'
    _title: 'Weather Settings form'
  requirements:
    _permission: 'administer site configuration'

WeatherSettingsForm.php

<?php

namespace Drupal\weather\Form;         

use Drupal\Core\Form\ConfigFormBase;
use Drupal\Core\Form\FormStateInterface;

/**
 * Configure example settings for this site.
 */
class WeatherSettingsForm extends ConfigFormBase {      
  /**
   * {@inheritdoc}
   */
  public function getFormId() {
    return 'weather_admin_settings';
  }

  /**
   * {@inheritdoc}
   */
  protected function getEditableConfigNames() {
    return [
      'weather.settings',
    ];
  }

  /**
   * {@inheritdoc}
   */
  public function buildForm(array $form, FormStateInterface $form_state) {
    $config = $this->config('weather.settings');

    $form['weather_api_key'] = array(
      '#type' => 'textfield',
      '#title' => $this->t('API Key'),
      '#default_value' => $config->get('weather_api_key'),
    );

    return parent::buildForm($form, $form_state);
  }

  /**
   * {@inheritdoc}
   */
  public function submitForm(array &$form, FormStateInterface $form_state) {
    $this->configFactory->getEditable('weather.settings')
      ->set('weather_api_key', $form_state->getValue('weather_api_key'))
      ->save();

    parent::submitForm($form, $form_state);
  }
}
?>