At DrupalEurope Dries announced that Drupal 8 will be end-of-lifed in 2021 and that Drupal 9 would be out sometime before November 2020. That gives us 2 years to get ready. Drupal 8 has replaced lots functionality and we’re going to remove the backwards-compatibility layers in Drupal 9. Drupal 8 does this by deprecating old code and using change records to tell users that their code needs upgrading. The good news is that we can also leverage other tools to find out when old code is being used and check this in automated testing. This talk will discuss: What is technical debt Using Drupal’s deprecation policy Detecting deprecations How to deprecate code Other recommendations for getting ready for Drupal 9 This talk is aimed at people who want to or do write PHP code for Drupal.