I was creating a function which creates a new custom post type with the category or taxonomy name if it was created from the post editor. I am simply using the wp_insert_post function with the taxonomy name as the post title and content and I am hooking the function to the save_post hook.

The function is working fine on the classic editor. However, it is not working on the new Wordpress block editor. Once I save the post, it gives me "Updating failed" message. On the console, it gives me internal server error:

Failed to load resource: the server responded with a status of 500 (Internal Server Error) with the REST API url as follows: http://localhost:8000/mywebsite/wp-json/wp/v2/posts/3447?_locale=user

I have checked the function and I made sure that the problem comes from the wp_insert_post function as updating the post works once I comment it out.

Here is the function:

    function add_new_term_from_post($post_id) {
      $settings_options = get_option('settings_options');
      if($settings_options['redirect-directly'] === "1") {

        $post_taxonomies = get_post_taxonomies($post_id);
        wp_defer_term_counting(true);

        foreach ($post_taxonomies as $post_taxonomy) {
          if (in_array($post_taxonomy, $settings_options['show_taxonomies'])) {
          $post_taxonomy_terms = wp_get_post_terms($post_id, $post_taxonomy);

          foreach ($post_taxonomy_terms as $post_taxonomy_term) {

            if($post_taxonomy_term->count === 1 ) {
          if($post_taxonomy_term->name !== NULL && $post_taxonomy_term->name !== NULL && $post_taxonomy_term->name !== NULL) {

    $term_post = array(
      'post_title'    => $post_taxonomy_term->name,
      'post_content'  => $post_taxonomy_term->name,
      'post_excerpt'  => $post_taxonomy_term->name,
      'post_status'   => 'publish',
      'post_type'     => 'whatever'
    );
    if(post_exists($post_taxonomy_term->name, "", "", "whatever") === 0) {
      wp_insert_post($term_post);
        }
      }

              }
            }
          }
        }
        wp_defer_term_counting(false);
      }
    }
    add_action('save_post', 'add_new_term_from_post');

If someone knows why this happens and how it could be overcome, I would be grateful. Thanks