Recompiling a derived blueprint with a child actor component crashes

Pressing the compile button in a blueprint can crash the editor with the following message:

Object 'REINST_Repro_Derived_C_1041 /Engine/Transient.World_11:PersistentLevel.Repro_Derived_C_0' is being used for execution, but its class is out of date and has been replaced with a recompiled class!

The setup to create this is as follows:

  1. Create a blueprint Base with a sphere collision component
  2. Create a blueprint Derived derived from the Base blueprint and add a child actor component to it
  3. Create a blueprint ChildActor with a static mesh in it
  4. Set the ChildActorComponent in blueprint Derived to be ChildActor
  5. Press compile in the blueprint editor

You can get the three relevant blueprints here (or just create them):

  • Base:
  • Derived: [][2]
  • ChildActor: [][3]


Just noticed the error is an ensure rather than an assert so you can continue from the break point as a work around.


Hi -

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Thank you -

Hello ,

I was unable to reproduce this issue on our end with a clean project. I have a few questions for you that will help reproduce this issue on our end.

Quick questions:

  1. Can you reproduce this issue in a clean project?
  2. If so could you supply any small steps that may have been over looked in the original post?
  3. Was the project that is having the issue upgraded from an older version of the engine?

Hello ,

We have not heard back from you in a few days, so we are marking this post as Resolved for tracking purposes. If you are still experiencing the issue you reported, please respond to this message with additional information and we will offer further assistance.

Thank you.