Frequent crash with 4.18 P2

I’m getting random crashes pretty often (sometimes when closing the editor and sometimes while compiling Blueprints) in 4.18 and the callstack points to MallocTBB.cpp file (line 130).

FMemory::Memset(Ptr, DEBUG_FILL_FREED, scalable_msize(Ptr));

This is the exception:

Exception thrown at 0x00007FFCE8662350 (UE4Editor-Core.dll) in UE4Editor.exe: 0xC0000005: Access violation reading location 0x0000000000000072. occurred

Here is a screenshot of the callstack.

Have you done any modifications to the engine? I.e. if you take a stock github build, will it also crash the same way on shutdown?

Hi RCL. This crash happens in the launcher build of 4.18.

Thank you RCL :). Would it be possible for you to check if this issue persists in promoted branch in GitHub?

Thanks a lot RCL :). Tomorrow when I get to office I’m cloning the promoted branch. I’ll let you know if the problem still occurs.

Thanks. Indeed - found it: Unreal Engine Issues and Bug Tracker (UE-47677) . I’ll let know folks who are investigating it.

It’s not yet fixed yet, so quite possible :slight_smile:

That said - try taking this change. It fixes an unrelated bug, but it is a memory corruption, so who knows… (For clarity - commit description calls out Linux, but memory corruption was happening everywhere - on Windows too).

Hello ryanjon2040-

If you do encounter this crash in the latest branch, please also include any setup / reproduction steps that lead to the crash to help us test the behavior locally.

Definitely Doug! :slight_smile: I just finished downloading promoted branch and applied RCL’s fix. Recompiling the Engine now. Will comment if this occurs again.

After posting this thread the Editor was crashing more often and even though it was completely random, one common thing I noticed was I had Anim Blueprint open most of the time.

For instance, here are the times when Editor crashed because of this error:

  • Dragging a pin from any variable in Anim Blueprint. Example: Float variable.
  • Exiting Editor while Anim Blueprint was open.
  • When Compile pressed in Anim Blueprint.
  • One random time while navigating the editor.

Ok so far I have not encountered this crash in promoted branch :). I think RCL’s commit fixed the issue.

Just a quick note. With this fix however a new crash is occurring when you press tilde ` key.

Hey ryanjon2040-

If you’re getting a crash, can you provide detailed information including the callstack from the crash and any repro steps? It would be best to do so in a new post so that the crash can be investigated without getting lost in this post.

Hi Doug, I have posted a new report here.

Hello Unreal Engine Devs, I am having the same issue with your newest update v4.18.2, having recently installed the engine, i have not modded the engine at all. I was opening up my pawns scripts and no matter what i do, i.e. Attach a function to a controller, or get a vector for a respawn, the game will crash instantly and slowly rack up my ram and disk untill everything crashes and im forced to restart my computer. I dont want to roll back because 4.18 has been a nightmare for me trying to use everything for vr, ive had to restart my entire game because it would not convert over from 4.17.2, and in doing so i crash everytime i pick up a few cubes and move around.