PIE Crash - UE-51886

Development World Creation
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1

I see you have marked UE-52280 fixed in 4.18.1, but the similar bug UE-51886 is not fixed. Our project is affected by UE-51886. PIE crashes every time after PIE window gets focused and gains mouse input.

PRECONDITION: Many streaming levels and streaming volumes in one level. Start PIE session with right clicking → Play From Here

HOWEVER there is no crash in PIE IF:
1.) PIE window is in full screen mode (F11)
OR
2.) Details panel is closed before starting PIE session (Details Panel could be the root cause for this bug?)

I can provide more information if needed, but those things stop Editor crashing so I suspect strongly that this bug is caused by new behavior of Details Panel. In my setup I have Details Panel, Levels Panel and World Settings Panels all as tabs under the same tab window. Whenever I unload (hide) streaming level in our project the Levels Tab is unfocused and Details Tab is focused. This itself is a minor inconvenience, but it could also be the reason for this bug I believe.

Just guessing here, but could the Details Panel try to show details of some object that is no longer available in PIE session after streaming level is unloaded?

2

I have managed to replicate a bug using plain project. It took me long to figure it out and I have been busy working…

I have minimal project done, but I have no means to upload it for now. I need to either find a way to upload or if you can replicate it on your own with my steps that would be great too. Maximum attachment size is about 5 megabytes, I try to get project down to that size…

Steps to replicate bug (Precondition):

  1. Create empty blueprint project (I used 3rd person blueprint project)
  2. Create streaming levels in the project (I created Level_A and Level_B which are inside a persistent world)
  3. Create streaming volumes for both levels and set levels to use those streaming levels.
  4. Have at least one clickable static mesh actor in both levels
  5. Go to Edit → Project → Maps & Modes → Default Pawn Class → Set to None

UI State:

  1. Have Details Panel visible (essential!)

Steps to crash editor after setting up project:

  1. Right click any static mesh actor in one of the levels
  2. Select “Play From Here” from the popup menu that opened
  3. Wait couple seconds until Editor crashes at:

UE4Editor_PropertyEditor!FObjectPropertyNode::GetValueBaseAddress() [d:\build++ue4+release-4.18+compile\sync\engine\source\editor\propertyeditor\private\objectpropertynode.cpp:373]

3

Here is Unreal Project that I had to strip out of almost all contents, but I can reproduce crash every time with this project, I hope this works.

Project should automatically open correct level (Repro_Persistent_World). You need to have Details Panel open up in editor to crash it.

  1. Right click any static mesh in Level B (It’s marked in the world as Level_B)
  2. Select “Play From Here” from the popup menu
  3. Wait couple seconds as Unreal Engine unloads Level_B (since Player Start is in Level_A, that’s where player spawns)
  4. Editor crashes

Here is what I believe happens (I don’t have deep enough knowledge of UE4 editor to actually step debug it):
Since there’s no default pawn class (pawn class selection is deferred) game spawns player camera at the (0,0,0) or where the Player Start is located at. This happens to be inside streaming volume of Level_A. As such, Level_B is now unloaded by engine. Editor tries to update contents of Details Panel, but it can no longer access the object that was selected by the right click, before PIE session was started using the popup menu.

So the deferred pawn class selection in conjunction with streaming level(s) unloading and Details Panel trying to access unloaded actor data results in crash.

link text

4

Thank you for the additional information. We where able to get a reproduction case for this issue.

Make it a great day

5

Hello Veheluuk,

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 follow up.

Thanks,

6

Hello Veheluuk,

Thank you for the additional information that was was provided. We were able to get a reproduction case for the issue mentioned on this thread.

Make it a great day

7

Hello Veheluuk,

After taking a look at the public tracker for UE-51886, it appears that it is still marked as unresolved. With this being the case I would expected that you would continue to have this issue. However, if you feel that you are having a separate issue/crash, I would be happy to investigate further.

Information that would be needed:

Quick questions:

  1. Can you reproduce this issue in a clean project?
  2. If so, could you provide a detailed list of steps to reproduce this issue on our end?
  3. Could you provide screen shots of any settings/blueprints that may be involved with this issue?
  4. Could you provide your complete callstack (included machine ID)
  5. Could you provide your logs?