The linked project crashes on open after attempting to implement an interface and a duplicate of that same interface with different function names. This has not been reproduced in a clean project, however the user has provided additional information on this issue:
"The engine asserts in UObject::SetLinker() . This is called because the engine wants to rename  an object (an interface function / a graph). This is strange because there should be no need to rename the function at this point in time! The ConformInterfaceByGUID()  function will rename interface functions if their GUIDs match but their name does not match. As it turns out there is the same "InterfaceGuid" for different interface functions. E.g. "Attack_BPI::IsAttackable" has the same GUID as "Skin_BPI::IsSkinnable" (1345967241-1227943219-3811549834-934607715).
I then reverted the project to the previous working state and put a conditional breakpoint into the FGuid::operator<<() to break whenever that above mentioned GUID is loaded. Then I duplicated the "Attack_BPI" blueprint-interface via the editor's context-menu and the breakpoint did hit! So it seems the GUID of the interface functions are copied to the duplicated blueprint-interface but they would need to be initialized with a new unique GUID instead.
We tried to reproduce the issue using a blank blueprint-only project but did not succeed, so "simply" duplicating a blueprint-interface does not always make the engine assert when restarting the editor and loading the project."
1. Open the project: [Link Removed]
2. Go into the NPCs folder
3. Duplicate Attack_BPI
4. Go into Attack_BPI2 and change the function names
5. Open NPC_Parent
6. Add the Attack_BPI2 interface
7. Save and Compile the blueprint
8. Restart the project
Result: Project crashes
Expected: Project would open successfully
Head over to the existing Questions & Answers thread and let us know what's up.