Crash, in the Blueprint Debugger

Crash occures when developer trying to step in the blueprint interface function, which not implemented in a invoking object.

Bug exist in a 4.18.1


  1. Create or open any UE4 project
  2. Create blueprint interface ‘BI_Test’, add ‘TestFunc’ funtion
  3. Create blueprint actor object ‘BP_TestDummy’, add ‘BI_Test’ as implemented interface. Do not implement ‘TestFunc’
  4. Create blueprint actor object ‘BP_ExecTest’, in Event Begin add spawning ‘BP_TestDummy’ and invoke ‘TestFunc’ in a spawned object
  5. Place ‘BP_ExecTest’ into the scene
  6. Place breakpoint in the ‘Invoke TestFunc’ node
  7. Start PIE
  8. When breakpoint hit, press ‘Step In’ two times

Link to pull request with my solution

Hello Giperion,

I have a couple of asks for you that will help me greatly.

First, could you provide the crash logs that you are receiving on this.

Second, if you could provide some screenshots of your Blueprints so I can see exactly how you are setting them up that would help a lot. If you have a small sample project that is experiencing the crash you can send that as well.

Lastly, the link that you posted at the bottom of the page does not actually lead anywhere, I am receiving a 404 error when following it.

Thank you.

Hello Jeff.
Thanks for reply. I decided to provide you everything =)

  1. Crashlog and minidump: link
  2. Sample project…: link
    …and series of screenshot ‘how to reproduce’: imgur albom
  3. Link that I provided you require the github account with EpicGames repository access, instructions here.

If you don’t have time to create a github account, just embend my link to bug report. I sure, other developer have access to UE4 repository.

Have a great day!

Hey Giperion,

A ticket has been created for this, you can follow it here UE-52621

Thank you.