subsystem

AUG 2026

reference

ShouldCreateSubsystem and the subsystem class hierarchy

The subsystem collection asks each non-abstract class's CDO whether to create an instance. A subclass does not automatically replace its parent; both can exist side by side. This explains how to move the implementation into Blueprint, how to keep a C++ fallback when the child is missing, and why GetSubsystem<T>() can still find the derived instance.

subsystem unreal-cpp blueprint cdo

13 Aug 2026

quick-tip

A Blueprint subsystem does not get created in a packaged build

The subsystem collection scans for subclasses once, when it is initialized, and sees only classes already in memory. In a packaged build, a Blueprint class that has not been loaded by then is missed entirely: its CDO is never asked whether to create an instance. The Blueprint logic never runs, and the missing class produces no error or log entry. In the editor, the Content Browser can keep the class loaded and hide the problem.

subsystem gameinstance blueprint packaging cooking

11 Aug 2026

JUL 2026

reference

Subsystem and manager actor lifecycles — who, when, and in what order

Five subsystem base classes, each with a different owner. Where the engine creates and tears down each collection, how world startup relates to actor BeginPlay, and where initialization order is no longer guaranteed.

unreal-cpp subsystem lifecycle world-partition

21 Jul 2026