Problem/Motivation
In #3087644: Remove Drupal 8 updates up to and including 88**, we noticed that using that hook_update_last_removed() is not actually that strictly enforced (it requires to have an update function), doesn't actually show what's going on and just displays a warning message, together with a success message:
Proposed resolution
Add something to system_requirements() that checks for that explicitly, for all modules implementing such a hook. Display an error with clear infos and don't allow users to continue in that case.
Remaining tasks
- Update the wording after #48: "Updating to Drupal 9 is only supported from Drupal version 8.8.0 or higher. If you are trying to update from an older version, first update to the latest version of Drupal 8." Consider making "latest version" or "latest version of Drupal 8" a link, as discussed in #51, #53.
- Update the "after" screenshot.
- Add a screenshot for the error message from a non-core module. Consider changing "earlier" to "intermediate".
User interface changes
(copied from #40)
Before:
you only get a warning that doesn't prevent you from doing the update and that warning only shows up on a later step when the updates are listed:
After:
Update.php stops on the requirements page and displays an error that doesn't allow you to continue:
