New Rails, new i18n, new warnings:

[DEPRECATION WARNING] Nested I18n namespace lookup under "activerecord.attributes.admin" is no longer supported
[DEPRECATION WARNING] Nested I18n namespace lookup under "activerecord.attributes.scanlation" is no longer supported
[DEPRECATION WARNING] Nested I18n namespace lookup under "activerecord.attributes.manga" is no longer supported
[DEPRECATION WARNING] Nested I18n namespace lookup under "activerecord.attributes.character" is no longer supported

From now on, you cannot use nested namespaced models translations. Lil bit weird since I remember, that when I’ve been moving from 2.3.7 to 3.0 I needed to do opposite thing.

Fix is easy to implement, just replace nested stuff like:

pl:
  admin:
    su: "Super user"

with slash separeted names:

pl:
  "admin/su": "Super user"

Same for attributes and warning will disappear.