Change record status: 
Project: 
Introduced in branch: 
8.0.x
Introduced in version: 
8.0.0-BETA8
Description: 

All usages of '#theme' => 'status_messages' must be converted to '#type' => 'status_messages'.

This ensures that each rendered messages are rendered using a placeholder to prevent the rendering of messages in a particular place on the page from breaking render cacheability.

Impacts: 
Module developers