Editor Crash when spawning Child of Child blueprint without manual recompile

Note: this is happening in the 4.12 Preview but this problem initially occurred in 4.11.2.

I have a Parent blueprint that when I load the editor up, if I do not manually recompile the Parent blueprint, when pressing play, the game launches and crashes the editor upon spawning a child of a child of that Parent (but spawns a first level child fine).

Conditions:

  1. Parent Blueprint has not been
    recompiled on this load of the
    editor
  2. Parent Blueprint has to be
    set to replicated and have a
    replicated variable in use
  3. Child of the Child of this Parent blueprint has to be spawned. If I spawn a first level Child of the
    Parent, no crash occurs, only a second level child crashes the editor
  4. 2 Players, Dedicated
    server are my Play settings
  5. Error
    log indicates failure point in
    Replayout.cpp, which makes sense
    given the problem only occurs when
    Replicated Variables are in use
  6. I cannot reproduce this in a blank project, so I imagine there is some
    sort of condition in my project
    blueprint that I cannot identify
    that doesn’t exist in a blank
    project, despite me making a
    child of a child of a parent
    blueprint with replicated
    variables set to replicate

Now, it makes no sense to begin with that the game will play fine if I recompile the blueprint manually, but crashes if I don’t, since the blueprint should be in the same state after compile as when loading the editor if I’ve made no change. If I compile the blueprint, save all, then reload the editor…the crash is right back. If I load the editor, hit compile on that one Parent blueprint, then hit Play, the game loads without a problem. Very odd.

I really need to maintain my blueprint structure as I want to ensure changes made later in the project propagate to all child classes. For now my workaround is to simply recompile the Parent blueprint every editor load, but I’m very concerned I’ll run into problems down the road when I go to finalize this project. Since I’m trying to build a kit to sell on the marketplace, this is particularly concerning.

I am currently in engine 4.12 Preview, but this issue started when I was still using 4.11.2, and I reinstalled 4.11.2 to try and rectify the issue with no success.

Hello WahaGames,

I have a few questions for you that will help narrow down what issue it is that you are experiencing.

Quick questions:

  1. Was this project upgraded from an older version of the engine when this issue started occurring?
  2. If so, did you delete your saved and intermediate folders before upgrading?
  3. If you did not, could you try deleting your saved and intermediate folders and let me know if this makes any difference?
  4. Could you try using File > Refresh all nodes on the blueprint that needs to be compiled?

Sir,

  1. No, it was created originally in 4.11.2 and the issue started in 4.11.2, the issue has just carried on through my various attempts to solve it, one of them being upgrading to 4.12 Preview.
  2. I did try this fix, as you suggested doing so in someone else’s bug post that I thought might fix my own issue. I will try again this evening and let you know if it changes anything since I’m now in a new version.
  3. I will try this again. I’m 99% sure I’ve done this, but as always…bug finding can be a pain so I’ll try again this evening and let you know the results.

As a couple other possible fixes if something less painful doesn’t present, I’m going to try and duplicate the parent blueprint and reparent all the children (this will break all my connection pins as it’s a variable type change). As a last resort, rebuild the blueprint. I could just do this now, but if there’s a legitimate bug I want to be sure it’s caught for future users.

Thank you for your help, you guys do good work.

Sir,

After performing the above steps as requested:

  1. Deleting the folders had no effect. They regenerated and reset the settings as expected, but the crash still occurred.
  2. Refresh All Nodes prevented the crash from occurring without having to compile, so it appears to circumvent the issue causing the crash. However, after saving/closing the project and reopening…the crash occurs if I simply hit play without refreshing nodes/recompiling. However, I have a feeling the point of that was to narrow down where the break is happening, not to fix the issue.

Does it sound like I have a single node in my blueprint somewhere that could be causing the whole issue?

The thing that surprised me most is that this blueprint is really quite simple compared to others.

No idea what happened, but the problem resolved itself. I didn’t even rebuild the blueprint that was needing to be recompiled each time. I was moving some code around and decided to try to crash the editor…and nothing.

So I guess…fixed.

Extra dumbfounded.

Hello WahaGames,

I am happy to hear that your issue has been resolved. I will be accepting your last answer. If this issue happens again please feel free to reopen this issue with any additional information that you may have. Thank you for your time and information.

Make it a great day