So, just installed unreal 5.5 preview, unfortunately, there is no change, it still crashes with lead pose component and GPU skin cache enabled.
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Just chiming in to say that I also have this issue… It was driving me crazy that I was crashing on certain scenes with seemingly no version controlled changes to those scenes are even assets found inside… very strange that turning on hardware ray-tracing would cause this crash!
Hi I’m getting this issue ever since I added Metahuman and did this follow leader for its parts using hardware raytracing is also enabled and so is skin cache, no idea what to do now might have to make the character into one piece somehow in Blender
(if anyone finds a fix ping me)
Hello there. It’s my 4’th all day long deleting the settings recompiling the shaders and so on. It happening also on mtahumans with leading pose , i did check Force update. And y’m using the manny skeleton as leader pose and metahuman as follower. I did tryed with gpu skin cache and raytrace on and off. Same problem crashes every time. And if i to does not at the first time after i put my metahumans (vendors) in game and reopen the project or move them arround. To be honest it driving me crazy and to see that are ppl around that had the same problem long time ago makes me nervous about it… what can we do? i mean y do have somehow to be able to work around this or change some fancy line of code inside who knows what file. Sooo Unreal stuff please look into this… if you do not solve this ower progress is doomed. Thank you
Hello there,
I think I found one possible explanation and was able to fix it (for my project at least): basically the mesh that was the leader in the leader pose setup was not setup (or badly setup) until after its “followers” meshes were setup and most likely displayed.
So try double checking the state and validity of your leader mesh before the rendering start and make sure it’s actually valid before trying to display any of its followers.
Can someone with the issue try to check it out?
Hm, how did you check the state and validity? I´ve dragged both lead pose and follower into the blueprint the same way, but the follower are getting called first in the blueprint, as I need to put them into arrays, before piping them into the lead pose.
So, you mean like, use the lead component with any nonsense node BEFORE the arrays get created, so it gets validated first or something?
I´m just a beginner with blueprints…
Also…I´m not actually displaying the lead pose leader skeletal mesh at all, as I´m using a layer based system to hide different parts of the mesh. So I just added ONE skeletal mesh using the same skeleton as all the other skeletal meshes to drive the animation, without actually being displayed anywhere (not sure if I set it to hidden in game or simply put a translucent material with 0 opacity on it to hide it).
That and the fact that its also crashing with metahumans, who were setup by epic themselves, makes me a bit less hopeful you actually found a solution for everyone by cleaning up your blueprint.
Still would like to know what you did exactly in your blueprint, so I can try to recreate it for mine.
I´ve tried so many different setups already, including a very simplified rig in a new and untouched project with all the default settings and it always crashed with raytracing.
It also didn´t always crash right away, but every time I reopend a previously saved map with the blueprint in it, it crashed.
ALSO…one more note for troubleshooting in case any devs chack in on this…:
It only seems to crash with raytracing in the editor viewport. I CAN actually open the blueprint when raytracing is enabled, without it crashing (afair).
But that might just be due to raytracing not actually being enabled in the blueprint viewport…
This still happens in 5.4.4. I am not sure what is the cause for this. I am also using SetLeaderPose Component, for a modular character system. The thing is, it didn’t happen before. It started today, out of nowhere. Can’t think of a related change I did to the character system, or anything related to SetLeaderPoseComponent. Perhaps, the only thing, is that I deleted all the cache (DerivedDataCache, Intermediate, Saved and Binaries).
Guys I fixed it. The issue what the the skeletal mesh on the skeletal mesh component on which all the child skeletal components were attached, was nullptr. Previously, I was always attaching it at runtime, but the reference to it somehow got lost so I had to attach it again, and it now works.
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Can you elaborate?
Based on my setup in the blueprint, where you use the lead pose component (in the construction script), what did you do different?
I´m tagging you in case you just missed the reply…but you´re not getting the plaque unless you can elaborate what you did to solve it…unless you didn´t actually solve it and it crashed again next time you opened the scene.
I´m downlloading 5.5.1 in the hope they caught the issue, but its probably still there and we still are no way closer to a solution.
Like I said: At this time I would be REALLY happy if someone could try to reproduce it and could NOT reproduce the crash, then at least I would know that I need to start looking at my hardware/drivers/unreal installation/cache and not hope there is gonna be fix from unreal.
I encountered the same issue last week.
In my case, the crash happened when I opened the map, not when starting PIE.
I tried every solution mentioned in this thread, but none of them worked for me.
Then, I started debugging the engine and found the problem.
It was an initialization order issue.
I had a Blueprint actor with two skeletal mesh components, like the one below:
DefaultSceneRoot
├ Leader
└ Follower
The engine attempted to register the ‘Follower’ component first, and the ‘Follower’ component tried to access the ‘Leader’ component, which wasn’t registered yet.
As a result, the ‘Follower’ component was initialized with invalid values, causing a crash.
The solution was to change the hierarchy, with ‘Leader’ as the parent:
DefaultSceneRoot
└ Leader
└ Follower
However, even after modifying my BP asset, I still suffered the crash.
This was because the engine tried to initialize the level with the already corrupted .umap file, not from the modified BP asset.
In the end, I modified the engine, opened the level, re-saved it with the modified BP, and then rolled back the engine changes.
And I was happy again! 
Here is the code I added at the start of FSkeletalMeshObjectGPUSkin::Update():
if (InMeshComponent && InMeshComponent->LeaderPoseComponent.IsValid() && !InMeshComponent->LeaderPoseComponent->IsRegistered())
{
InMeshComponent->LeaderPoseComponent->RegisterComponent();
}
I hope this helps!
Thanks for taking the time to add your steps, I´m not quite sure I understood though:
The code snippet you added to the engine was only necessary to fix the problem with the umap file?
So, if I don´t need to work with that level and could just create a new one and add the blueprint to that one, I wouldn´t need to add that code?
Or does that code need to be added to the engine permanently? Because I´ve never tinkered with the engine itself…
I´m gonna try to recreate this right away in a fresh project, to see if that fixes the problem.
The code snippet is only to fix problem with the umap file.
If you don’t have any problems opening the map, it’s not necessary.
We also had this issue and needed RT only for light baking. The other solutions here didn’t work for our case, but what did work was the following: disabling skeletal mesh raytracing altogether. Since we didn’t need RT at runtime and you never bake a skeletal mesh anyway, this worked for this specific case, so I hope posting it here might also help others.
To do so, add the following to the [/Script/Engine.RendererSettings] of your DefaultEngine.ini:
r.RayTracing.Geometry.SkeletalMeshes=0
r.RayTracing.Geometry.SupportSkeletalMeshes=0
Oh, thats a very interesting idea, gonna have to try that asap…
I´m carefully optimistic that the problem might indeed be one of hierarchy…
I first tried a clean project and just recreated a simple lead/follow blueprint.
As I couldn´t reproduce the crash with raytracing, I followed by importing a metahuman (since those are already set up with lead pose by default and had previously also crashed).
And then I couldn´t reproduce the crash again.
I tried very slowly, going step by step, especially I didn´t just confirm all the missing plugins and settings and instead enabled them one by one.
Doing so I noticed that some Cvars were missing from my project, that the metahuman import told me to add:
// This might have been missing for raytracing and lead pose to work
r.GPUSkin.Support16BitBoneIndex=True
r.GPUSkin.UnlimitedBoneInfluences=True
SkeletalMesh.UseExperimentalChunking=1
So, next step was to add those to my current project with the crashes.
tried again with a default metahuman, no crash.
Then reloading the map: Still no crash.
Then I proceeded with my actual blueprint.
Same thing: No crash at first with raytracing.
But then upon reload, I got the same crash.
So, all I did then was to change the hierarchy (the follow meshes also weren´t linked to the lead component) and now it seems to run stable even after reloading…
I´d like to run some more tests to finally confirm this as SOLVED, but I ran out of time today…
A few more ideas as to the previous inconsistencies:
-They might have been caused by reusing the same level, so after crashing the level once with the wrong setup, even the (now working fine) metahuman would crash, once that level got corrupted.
-They might have changed something with the metahuman validation order, but I don´t think so.
-Those Cvars might have been missing and added to the problem, but thats also unlikely.
Your solution makes sense, and yeah, it seems to be working now, I´ve just had soo many “Its working!!!..oh wait, its not” moment with this issue, that I´d like to be able to reproduce the problem rather than figuring out its still broken a week later…
To anybody else experiencing this issue…pls check if this also fixes it for you!
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If for somebody helps, in my case was a destructible component in a BP, removed and my problem solved
Hm, looks I do need to fix some corrupted levels after all…
not sure how you did this, based on your post, where do you edit these? Tried opening the .umap files in visual studio, but couldn´t find those lines…
And wouldn´t it maybe just work to rebuild the DDC?
I´ve only done this once and it takes quite a while due to the size of these projects, so I don´t wanna just try and hope for the best…
But again: On new levels, whith the correct parenting, it seems to not crash anymore with raytracing enabled!
So, great progress, thanks to you…
Oh, I used the entire source code from GitHub. (SkeletalRenderGPUSkin.cpp)
If you didn’t, you might not have that file.