UE4 Crash after PIE due to UMG?

[Mopperl]

Greetings!

I’ve created a small test Inventory with UMG, and added Drag and Drop Functionality, everything works fine way I want, line Traces check out fine, there is no errors or warnings, however a strange behaviour occurs in following circumstance:

If I move an Item between Slots and Item is inside a Slot it was in before (i.E move from Slot 0 to Slot 1 then back to slot 0) and then close out PIE Editor crashes.

If I move Item as such Slot 0 > Slot 1 > Slot 0 > Slot 2, it works fine…

Error I recieve:

MachineId:4F771C954F69C78D7E97319D9BFB19A3
EpicAccountId:0a9831451b034ef3ba3021766cd9fcb3

Unknown exception - code 00000001 (first/second chance not available)

Fatal error: [File:D:\BuildFarm\buildmachine_++depot+UE4-Releases+4.5\Engine\Source\Developer\MessageLog\Private\Model\MessageLogListingModel.cpp] [Line: 70]
Critical Error InputComponent //Game//Maps//UEDPIE_2_TutorialTown.TutorialTown:Persistent

KERNELBASE + 37901 bytes
UE4Editor_Core + 3174852 bytes
UE4Editor_Core + 1677215 bytes
UE4Editor_MessageLog + 241173 bytes
UE4Editor_MessageLog + 241423 bytes
UE4Editor_Core + 1077733 bytes
UE4Editor_UnrealEd + 4172422 bytes
UE4Editor_UnrealEd + 1898852 bytes
UE4Editor_UnrealEd + 6486374 bytes
UE4Editor!FEngineLoop::Tick() + 3524 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.5\engine\source\runtime\launch\private\launchengineloop.cpp:2129]
UE4Editor!GuardedMain() + 479 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.5\engine\source\runtime\launch\private\launch.cpp:133]
UE4Editor!GuardedMainWrapper() + 26 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.5\engine\source\runtime\launch\private\windows\launchwindows.cpp:125]
UE4Editor!WinMain() + 249 bytes [d:\buildfarm\buildmachine_++depot+ue4-releases+4.5\engine\source\runtime\launch\private\windows\launchwindows.cpp:201]
UE4Editor!__tmainCRTStartup() + 329 bytes [f:\dd\vctools\crt\crtw32\dllstuff\crtexe.c:618]

[anonymous_user_33800a51]

Hi Mopperi,

I’d like to try to reproduce this crash, but I’ll need more details on your setup. If you provide some screenshots of your UMG and BP graphs, I might be able to do so with that. If you’re able to upload a test project with which this crash occurs and send me a download link, I can test with that.

Please also and attach crash log and dump file for your project after this crash occurs. Thanks!

[Mopperl]

Hello! Here you go,

I hope you can figure out whats going wrong there.

Draggable Object

Slot wich it is dropped into

Creation of Inventory Grid and populating it[link text][3]

[Mopperl]

Err added new comment instead of reply whoops but yeah see below!

[anonymous_user_33800a51]

crash log refers to BP_XiaProxy still being referenced. There isn’t enough information available in these screenshots to reproduce error on my end. Would it be possible to upload your project somewhere and send me a link? You can do so via PM on forums if you prefer.

[Mopperl]

XiaProxy is Player’s Pawn, it creates and holds Inventory Actor, wich in turn consists of Inventory Functions and an Array of Inventory Items.

I managed to narrow down Issue however, I tried to redo Inventory step by step and Crash started appearing after I added these two:

Note that now referenced Actor causing PIE crash is Inventory Actor (In older crashlog I tried getting inventory via cast to Proxy hence it being referenced.

I reference Inventory Actor UMGWidget belongs to when it is created.

I’m not sure how else I would access it since casting to pawn and getting it from there caused a similar issue

[Mopperl]

Played around with diffrent ways of populating inventory Widget, but it still comes back to crash, have you been able to recreate it with last screenshot?

[anonymous_user_33800a51]

Unfortunately no, but you have a lot of different Blueprints being referenced and I can’t see how they all connect with each other. My guess is that you have some cyclical dependency issues going on here that crashes under a particular circumstance, but it’s hard to track those down.

[Mopperl]

Alright, I’ve tried isolating just inventory stuff to send to you and funny enough on it’s own it works perfectly fine, how something that must be unrelated causes crash is beyond me but I’ll keep looking for a cause and report back when I find it.

[anonymous_user_33800a51]

Thanks for test project! I saw bug you are describing, and I conferring with UMG developers to see what might be causing it. Right now we believe it may be a garbage collection issue. I will let you know what we find.

[anonymous_user_33800a51]

Hi Mopperl,

Sorry for really long delay! It took some time, but developers were able to isolate issue (UE-7234) and have fixed it internally. fix was deemed Critical, so it should make it into official 4.7 Release. Again, sorry for delay, but hopefully this will still be useful for you. Thanks for report!