This seems to be quite a pain in the ass.
Official release note states “Update Drush to 8.1.12 or higher before using it to update to Drupal core 8.4.x”. Yet, on one hand Drush 8 does not officially support Drupal 8.4 and on the other hand Drush 9 does not include features to update core/modules as it is now dedicated to composer’s job (as far as I have now understood). Then if you have Drush installed as a dependency in /vendor/dush folder and you do “drush up” the first step what the command does is to delete itself (i.e. /vendor folder) and thus the update fails. So why is the release note describing this as a tool to update D8.3 to D8.4? This serves no one.
This is kinda crazy situation where the role (and install and update method) of Drush changes “every day” (every major version). It might be ok for experienced developers, but for a beginner this is unsuitable. Although I have worked for years with Drupal this is now going over the roof.
What I am asking are clear guidelines how to do the update and that these guidelines would stay the same for the whole lifetime of D8. https://www.drupal.org/docs/8/update/update-procedure-in-drupal-8 These guidelines seem to be now outdated with Drush 9 and D8.4 and they are definitely totally gibberish for a beginner.
I am not requiring WordPress styled updates (although I wouldn’t mind if that happened), but some real stability would be nice 🙂