Migration

In the middle of its life cycle, Drupal 8 introduced in core Media, and for about a year, continued to add functionality until it became usable. Media has a library, allows reusability, and allows adding custom fields to the media entities. Some of the websites I worked with were built with the file_entity module that made the files fieldable, and entity_browser module, which provided a UI library for reusing files. That module combination is incompatible with Media and needed to be dismantled, but not before the functionality got migrated to Media. Here are some thoughts on this process.
Drupal 8 is supported until November 2, 2021. All Drupal 8 sites need to be upgraded to Drupal 9 by then. Drawing from the lessons of hard and painful migration from Drupal 7 to Drupal 8, Drupal devs have decided to make the transition from 8 to 9 as smooth as possible. Reading tweets and blog posts it may seem "it's just the matter of running update.php". Is it though? Here are some things you may want to know.