How to redirect user after submitting an article?
Yes, form_alter and a custom submit handler was the solution.

function _custom_admin_form_node_article_form_alter(&amp;$form, FormStateInterface $form_state, $form_id) {
  foreach (array_keys($form['actions']) as $action) {
    if ($action != 'preview' &amp;&amp; isset($form['actions'][$action]['#type']) &amp;&amp; $form['actions'][$action]['#type'] === 'submit') {
      $form['actions'][$action]['#submit'][] = '_custom_admin_article_form_submit';
    }
  }
}

function _custom_admin_article_form_submit($form, FormStateInterface $form_state) {
  drupal_set_message(t('Thank you for submitting an article.'));

  $url = Url::fromRoute('&lt;front&gt;');
  $form_state-&gt;setRedirectUrl($url);
}