I'm excited to be discussing migration in Drupal 8 at the next Drupal Cape Town meetup, Wednesday the 27th of February 2019. The broad outline of my talk is:
I was contracted by LAB to manage the migration of content from the old IAB website (Drupal 7) to an under construction, Drupal 8, IAB UK website. I successfully set up and ran migrations for 16 Drupal 7 content types (including some with field collections), to some fairly complex, paragraph based, new Drupal 8 content types. This included document and image migration, as well as taxonomy migration. Some custom migration plugins had to be created to convert data from the old site into the correct format that the new site required.