If you implement the hook_menu_links_discovered_alter() hook in Drupal 8.3 you have access to change the links with a code like this:

/**  * Implements hook_menu_links_discovered_alter().  */ function onlyone_menu_links_discovered_alter(&$  links) {     $  links['node.add.article'] = t('New name'); } 

This code comes from the issue Improve the Add content page for the Allow a content type only once (Only One) module. But starting from Drupal 8.4 the same code gives an error like this:

Notice: Undefined index: node.add.article in onlyone_menu_links_discovered_alter()

I searched inside the Drupal change records but I don’t find anything talking about this change.

Now in Drupal 8.4 how you can change a link title?