All information is in THIS thread, but I’m making a new report as @ suggested.
The warnings shows on a new, clean project on official 4.9. Reproduction steps are the same, created by @:
Make a new project.
Add new blueprint, based on actor, this is the parent.
First add a static mesh component to it then a scene component.
Compile. No warning in the log.
Make a new BP based on this, the child.
Add a scene component to it.
Compile. No warning.
Go back and compile the parent again, even tho it has not changed. The warning should show up.
The warning shows in Output Log window (it does not pop up by itself, Output Log window must be opened to see the warning) :
“LogBlueprint:Warning: USimpleConstructionScript::FixupRootNodeParentReferences() - Couldn’t find inherited parent component ‘DefaultSceneRoot’ for ‘Scene1’ in BlueprintGeneratedClass ‘REINST_Child_C_43’ (it may have been removed)”
I managed to reproduce this and have entered a bug report, UE-20632, to be assessed by the development staff. As before this log warning does not seem to have any adverse effect on projects, it is simply a warning in the logs and will not decrease performance. If you do notice a performance drop related to this error, please let me know and I’ll take another look.