I’ve just upgraded a project from 5.7 to 5.8 and having repeated crashes upon trying to add target paint layers (need 7) and now with trying to add a landscape layer (need 3) for splines. Error relates to “Too many residency sets are open concurrently”. Never had these issues with 5.7, so just wondering if this is a known issue and if so, whether there is a solution?
Hello there @Astro-Chris!
Since you just finished a project migration, I would strongly suggest clearing your project’s cache, as it’s likely loaded with stale data, creating the crashes you are seeing.
To do so, go to your project’s main directory, and delete folders Saved, Intermediate, and DerivedDataCache. After that, re-open the project, allow it to rebuild, and try to setup a new spline. Also, for isolation testing, open a clean project in 5.8, and try to repeat your process, to check for potential crashes.
If the issue remains active, please share your crash logs and any errors you get here, then we will continue investigating.
Thanks for responding @brs-sebascova. Removed the directories and rebuilt, but still crashing upon trying to add a spline edit layer. Also tried it with a clean install and can add the spline edit layer fine. Here is the crash screen and zipped directory. Something to do with D3D12RHI residency but I never had similar issues with this in UE5.7 and even had more edit layers there (my 5.7 used DX12 as well). There is a note about raising “max_num_concurrent_cmd_lists”, but as I think (?) it’s there to protect the GPU, I’m wary of doing so.
UECC-Windows-DEF6FB5C424D061F5795FEACF806CB46_0000.zip (660.5 KB)
Hello again, and thank you for sending the full crash reports. Going through your logs, and checking with my peers, I think we can figure what’s going on.
For starters, looking around the community, the “MAX_NUM_CONCURRENT_CMD_LISTS” refers to the number of tracking slots available in DirectX, which your process seems to run out of. From your main log, the important entry is the following:
LogD3D12RHI: Warning: Descriptor cache ran out of sub allocated descriptor blocks!
Moving to Context local View heap strategy
LogD3D12RHI: This should only happen in the Editor where it doesn’t matter as much.
If it happens in game you should increase the device global heap size!
So, the descriptor runs out of blocks, moves to context local view heap strategy, and starts repeating heaps until DX runs out of slots to track it. Then the whole thing crashes:
[2026.09.17-14.10.49:585][222]LogSlate: Window ‘Pick Landscape Edit Layer Class’ being destroyed
[2026.09.17-14.10.52:744][223]LogD3D12RHI: Error: pSet->Open() failed at D:\build++UE5\Sync\Engine\Source\Runtime\D3D12RHI\Private\D3D12Residency.h:160 with error E_FAIL
No command list slot was available. Too many residency sets are open concurrently. Consider raising MAX_NUM_CONCURRENT_CMD_LISTS in d3dx12residency.h
Then, the breadcrumbs file entry refers to where the process failed:
Breadcrumbs ‘RHIThread’
RenderGraphExecute - UpdateAllPrimitiveSceneInfos
PerformLayersWeightmapsBatchedMerge
WorldTick
Frame 6223
This would explain why the operation works in a clean project, since the descriptor never falls back to local view heap strategy in default parameters. The issue is tied to the migrated project.
To fix it, try giving it what the log’s asking for, an increase to D3D12 local view heap size. You can adjust it with cmdlet D3D12.LocalViewHeapSize in engine, or make it a fixed change by adding it to your DefaultEngine.ini file. After that, please test adding a new spline landscape layer.
I raised the heap size to 1,000,000 from 500,000 using this command in the [ConsoleVariables] section of defaultengine.ini:
D3D12.LocalViewHeapSize=1000000
which seems to be the limit as I could not raise it more without the editor crashing on launch. I also tried changing it using the editor console command, but it had no effect. It would only change from the defaultengine.ini file.
However, it continues to crash when I try to add a spline edit layer.
Quick update: I’ve managed to add a spline layer by dropping down to D3DX11 temporarily, and so far it hasn’t crashed when I’ve restarted the editor in D3DX12. That said, I worry that I might encounter the error again when I start to work with layers.