Change record status: 
Project: 
Introduced in branch: 
8.x
Description: 

Custom textgroup support was removed from locale. This was only used in i18n and the module itself is migrating away from using that in Drupal 7 already. Configuration translation is solved with its own system, not by overriding locale module.

hook_locale() has been removed with no replacement.

Most translation that was previously handled by text groups should be handled by configuration or entity translation.

Impacts: 
Module developers