Description

This occurs because there exists a circular reference between the nativized parent BP and the non-nativized child BP asset (which is a data-only Blueprint in this case).

Current suggested workaround is to force the child BP to be nativized as well, by adding a dummy variable or component to the 'ChildBP' asset.

A crash will still occur with EDL disabled as well, although the callstack/assert will be different.

Steps to Reproduce
  1. Launch UE4 editor with a new blank C++ project.
  2. Create a new Actor-based Blueprint class (ParentBP).
  3. Right-click the ParentBP asset and choose "Create Child Blueprint Class" and name it 'ChildBP'.
  4. Double-click 'ParentBP' to open it for editing.
  5. Add a new variable of type 'ChildBP->Class'.
  6. Compile and set the default value to 'ChildBP'.
  7. Close the BP editor.
  8. Drag an instance of 'ChildBP' into the "Untitled" map and save it as "MyMap."
  9. Choose "Edit->Project Settings" and under "Packaging" change the nativization method to "Inclusive," then close the settings editor.
  10. Choose "File->Package Project->Windows->Win64" and wait for packaging to complete.
  11. When packaging completes, double-click the staged EXE to launch it, then type 'open MyMap' at the console. A crash should result:
    [2017.08.09-21.48.37:603][124]LogWindows: Error: === Critical error: ===
    [2017.08.09-21.48.37:603][124]LogWindows: Error: 
    [2017.08.09-21.48.37:603][124]LogWindows: Error: Fatal error: [File:D:\dev\Epic\UE4\Dev-Framework\Engine\Source\Runtime\CoreUObject\Private\Serialization\AsyncLoading.cpp] [Line: 1367] 
    [2017.08.09-21.48.37:603][124]LogWindows: Error: Async loading event graph contained a cycle, see above.
    

Have Comments or More Details?

There's no existing public thread on this issue, so head over to AnswerHub just mention UE-48233 in the post.

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Fixed
ComponentGameplay - Blueprint
Affects Versions4.154.164.17
Target Fix4.20
Fix Commit3952977
Main Commit3967553
Release Commit4095966
CreatedAug 9, 2017
ResolvedMar 19, 2018
UpdatedMay 31, 2018