I’ve just upgraded to 4.21 and decided to try Niagara. Created an emitter, a system and attached a NiagaraComponent to my character. Everything looks cool, but now every time when I try to recompile my project (with c++ through VS or Editor) Unreal Editor crashes…
Here is the stack trace:
Still occurring in 4.21 … In my case, I’ve been able to confirm that it is caused by a Particle System asset. I can use my version control to switch between a previous and current revision of a Particle System and with the previous revision, I can hot reload OK. I am still trying to figure out what’s different in the new one to see if I can reproduce this reliably with any Particle System. Further, I can remove all emitters from the system so it is completely empty and does nothing, and it still crashes the hot reload. Feels like a form of uasset corruption.
I have the same error when activating GPU system in the emitter. Once the asset is loaded the error will occur at the next hot reloading. Close it or delete it doesn’t prevent the error, you have to close the project and restart it without opening the asset to be able to hot reload.
Disabling GPU doesn’t suppress the error. The asset seems to keep some state that trigger the error.
The async loading thing didn’t help me either.
Still happening in 4.21.2! Why isn’t there more uproar about this? It’s murdering iteration times. Is there a bug for this registered somewhere? Are people not using niagara? Or big dev houses have a local fix? Is there a workaround other than pulling the engine from git and using an older version? ( though we’re excited about new niagara updates )
I have the same issue and I didn’t manage to reproduc it in a blank project… Did someone have any clue why ?
I already try to cleanup all my project folders (.sln, intermediate, binaries, …) without success.
(I need a way to reproduce it if I want to report the issue …)
Edit : I managed to found the reproducing steps thanks to @ShannonGreenwood using “GPUSim” in the emitter and send it to Unreal Support. I’m now waiting for their answers and/or the creation of the issue.
Update : I received an answer from the Unreal support :
“While I was able to reproduce your crash with your project, I have also confirmed that this issue no longer occurs in future versions of the engine. Please stay tuned for future updates.”
Unfortunatly yes!
I even tried to copy all my C++ classes, used same plugins and copied settings files (.ini) in the fresh blank C++ project. I’m still trying but no success, I can’t figure it out! First time i’m hopping the engine crash…
submitted a bug before I figured out how to reproduce - I don’t know how to find that bug now? Should I be able to search for it? Should I have gotten an email about it?
To repro:
have gpu sim enabled on a niagara emitter and c++ hotloading will crash
Yesterday - I tried migrating all of my niagara systems into an empty project - maybe the offending niagara emitters weren’t loaded and the crash didn’t happen. When I changed one of the emitter to gpu sim today, I started getting the crash.
You’re right!
I just changed the emitter to “GPU sim” and use the “Full rebuild” then “Compile” and it crashed.
I was able to send the reproducing steps to unreal thanks to you!
It may work, but I’m pretty sure it’s here to prevent some Access Violation from this thread to the game thread. But it seems fair to trade an every time crash with an eventual crash.
“While I was able to reproduce your crash with your project, I have also confirmed that this issue no longer occurs in future versions of the engine. Please stay tuned for future updates.”
Sorry. I should have been more specific.
I changed the file here C:\Program Files\Epic Games\UE_4.21\Engine\Plugins\FX\Niagara\Source\Niagara\Private
But it’s not doing anything. The error message still refers to a file. D:\Build\++UE4\Sync\Engine\Plugins\FX\Niagara\Source\Niagara\Private\NiagaraCommon.cpp but I dont have a d drive