Blender 5.1.0 Hangs or crashes while rendering (stuck on "compositing" or "finishing") using denoise nodes on some render passes in the compositor. #36

New Issue

Triager-bot · 2026-04-12T17:20:16Z

Triager-bot commented

2026-04-12 17:20:16 +00:00

Original bug report: https://projects.blender.org/blender/blender/issues/157210

System Information
Operating system: Linux-6.19.11-1-cachyos-x86_64-with-glibc2.43 64 Bits, WAYLAND UI
Graphics card: NVIDIA GeForce RTX 4070 Ti NVIDIA Corporation NVIDIA 580.142 Vulkan Backend

Blender Version
Broken: version: 5.1.0 branch: makepkg (modified), commit date: 2026-03-16 18:50, hash: adfe2921d5f3
Worked: 5.0.1.

Short description of error
Blender hangs(freezes), sometimes crashes while rendering using any compositor node on render passes.

Exact steps for others to reproduce the error

Use Cycles.
Set GPU Compute, 16 Samples Viewport with Optix Denoise and 64 Samples Render with Optix denoise.
Set Film<Transparent, GPU Compositor.
Set 4096x2304 resolution.
Select Diffuse Direct and Ambient Occlusion passes.
Go to the compositor, replace "Group Output" with "File Output".
Connect Diffuse Direct and Ambient Occlusion on "File Output".
Add Denoise Node on Diffuse Direct and Ambient Occlusion.
Render the project. Only for a few moments it just renders normally. If I render again, it will hang at "Compositing" or "Finishing", sometimes it crashes. I tested this on my main projects and experienced the same issues.

Final Note: GPU Compositing on Blender 5.1.0 is way slower than 5.0.1 version.

Original bug report: https://projects.blender.org/blender/blender/issues/157210 **System Information** Operating system: Linux-6.19.11-1-cachyos-x86_64-with-glibc2.43 64 Bits, WAYLAND UI Graphics card: NVIDIA GeForce RTX 4070 Ti NVIDIA Corporation NVIDIA 580.142 Vulkan Backend **Blender Version** Broken: version: 5.1.0 branch: makepkg (modified), commit date: 2026-03-16 18:50, hash: `adfe2921d5f3` Worked: 5.0.1. **Short description of error** Blender hangs(freezes), sometimes crashes while rendering using any compositor node on render passes. **Exact steps for others to reproduce the error** - Use Cycles. - Set GPU Compute, 16 Samples Viewport with Optix Denoise and 64 Samples Render with Optix denoise. - Set Film<Transparent, GPU Compositor. - Set 4096x2304 resolution. - Select Diffuse Direct and Ambient Occlusion passes. - Go to the compositor, replace "Group Output" with "File Output". - Connect Diffuse Direct and Ambient Occlusion on "File Output". - Add Denoise Node on Diffuse Direct and Ambient Occlusion. - Render the project. Only for a few moments it just renders normally. If I render again, it will hang at "Compositing" or "Finishing", sometimes it crashes. I tested this on my main projects and experienced the same issues. Final Note: GPU Compositing on Blender 5.1.0 is way slower than 5.0.1 version.

Dummy.zip

387 KiB

Compositor Nodes.png

54 KiB

Triager-bot added the

Status

Needs review

label 2026-04-12 17:20:16 +00:00

Triager-bot commented

2026-04-12 17:20:31 +00:00

Report is clear

LLM Reasoning

Got it, let's see. The user is asking if the bug report clearly describes the issue. First, I need to check the clarity of the text and steps to reproduce.

The title mentions the problem: hangs or crashes during rendering with denoise nodes on some passes in compositor. The body has a short description, exact steps. Let's go through the steps:

Use Cycles.
Set GPU Compute, samples, denoise settings.
Film settings (Transparent, GPU Compositor).
Resolution 4096x2304.
Select Diffuse Direct and AO passes.
Replace Group Output with File Output, connect those passes.
Add Denoise Node to both.
Render. Then it hangs or crashes at compositing/finishing.

The steps are detailed enough for someone to reproduce. The description of the error is clear: hangs/freezes, sometimes crashes when using compositor nodes on render passes. So the bug report's text and steps seem clear. So the answer should be Yes.

JSON Data

{
"llm_judgement": true,
"processing_time": 12.034270000000001
}

### Report is clear <details> <summary>LLM Reasoning</summary> Got it, let's see. The user is asking if the bug report clearly describes the issue. First, I need to check the clarity of the text and steps to reproduce. The title mentions the problem: hangs or crashes during rendering with denoise nodes on some passes in compositor. The body has a short description, exact steps. Let's go through the steps: - Use Cycles. - Set GPU Compute, samples, denoise settings. - Film settings (Transparent, GPU Compositor). - Resolution 4096x2304. - Select Diffuse Direct and AO passes. - Replace Group Output with File Output, connect those passes. - Add Denoise Node to both. - Render. Then it hangs or crashes at compositing/finishing. The steps are detailed enough for someone to reproduce. The description of the error is clear: hangs/freezes, sometimes crashes when using compositor nodes on render passes. So the bug report's text and steps seem clear. So the answer should be Yes. </details> <details> <summary>JSON Data</summary> { "llm_judgement": true, "processing_time": 12.034270000000001 } </details>

👍 1

Triager-bot commented

2026-04-12 17:20:44 +00:00

Report is specific

LLM Reasoning

Got it, let's analyze this bug report. The question is whether it's specific or generic.

First, let's recall the definitions: Specific means a detailed issue with exact steps to reproduce, while Generic is vague.

Looking at the report: It has an exact title about Blender 5.1.0 hanging/crashing during rendering with denoise nodes on some render passes in compositor. The body includes specific steps (using Cycles, GPU Compute, specific samples, resolution, selecting passes, replacing Group Output with File Output, adding Denoise Node, etc.). Also mentions it's reproducible and tested on main projects.

So this is a specific issue because it has detailed reproduction steps and a clear scenario (denoise nodes on render passes in compositor causing hang/crash). The system info is there but the key is the exact steps and specific context. So the answer should be 'Specific'.

JSON Data

{
"llm_judgement": true,
"processing_time": 11.989601
}

### Report is specific <details> <summary>LLM Reasoning</summary> Got it, let's analyze this bug report. The question is whether it's specific or generic. First, let's recall the definitions: Specific means a detailed issue with exact steps to reproduce, while Generic is vague. Looking at the report: It has an exact title about Blender 5.1.0 hanging/crashing during rendering with denoise nodes on some render passes in compositor. The body includes specific steps (using Cycles, GPU Compute, specific samples, resolution, selecting passes, replacing Group Output with File Output, adding Denoise Node, etc.). Also mentions it's reproducible and tested on main projects. So this is a specific issue because it has detailed reproduction steps and a clear scenario (denoise nodes on render passes in compositor causing hang/crash). The system info is there but the key is the exact steps and specific context. So the answer should be 'Specific'. </details> <details> <summary>JSON Data</summary> { "llm_judgement": true, "processing_time": 11.989601 } </details>

👍 1

Triager-bot commented

2026-04-12 17:20:59 +00:00

Report flagged as NOT a duplicate by LLM

Enabling the real time compositor when a denoise node is present in the compositor tree hangs blender.

https://projects.blender.org/blender/blender/issues/115156

System Information
Operating system: Linux-5.15.0-88-generic-x86_64-with-glibc2.35 64 Bits, X11 UI
Graphics card: NVIDIA GeForce RTX 2060 SUPER/PCIe/SSE2 NVIDIA Corporation 4.6.0 NVIDIA 525.147.05

Blender Version
Broken: version: 4.0.1, branch: blender-v4.0-release, commit date: 2023-11-16 16:40, hash: d0dd92834a08
Worked: (newest version of Blender that worked as expected)

Short description of error
When having a denoise noide in the compisitor nodetree, enabling viewport compositing hangs blender.

Exact steps for others to reproduce the error

Open default scene.
Open compositor workspace.
Insert denoiser node into graph.
Switch to layout workspace.
Switch to rendered mode an set viewport compositor to 'always'.
Blender hangs (or is so slow, as to be indistinguisable from hanging on my machine).

LLM Reasoning

Got it, let's analyze the two bug reports. First, look at the description and steps.

Bug Report 1: Focuses on rendering with denoise nodes in compositor causing hang/crash during compositing/finishing. Steps involve using Cycles, specific render settings, adding denoise nodes to passes, then rendering.

Bug Report 2: About enabling real-time compositor (viewport compositing) when a denoise node is present, leading to hang. Steps are opening default scene, adding denoiser node, switching to rendered mode with viewport compositor always on.

The key differences: Bug 1 is about render (final output) compositing during rendering process, while Bug 2 is about real-time (viewport) compositing when enabling it. The scenarios are different—render vs. viewport. So they're not the same issue. Therefore, answer is No.

JSON Data

{
"llm_judgement": false,
"processing_time": 13.606653999999999,
"duplicate_report_number": "115156"
}

### Report flagged as NOT a duplicate by LLM <details> <summary>Enabling the real time compositor when a denoise node is present in the compositor tree hangs blender.</summary> https://projects.blender.org/blender/blender/issues/115156 **System Information** Operating system: Linux-5.15.0-88-generic-x86_64-with-glibc2.35 64 Bits, X11 UI Graphics card: NVIDIA GeForce RTX 2060 SUPER/PCIe/SSE2 NVIDIA Corporation 4.6.0 NVIDIA 525.147.05 **Blender Version** Broken: version: 4.0.1, branch: blender-v4.0-release, commit date: 2023-11-16 16:40, hash: `d0dd92834a08` Worked: (newest version of Blender that worked as expected) **Short description of error** When having a denoise noide in the compisitor nodetree, enabling viewport compositing hangs blender. **Exact steps for others to reproduce the error** 1. Open default scene. 2. Open compositor workspace. 3. Insert denoiser node into graph. 4. Switch to layout workspace. 5. Switch to rendered mode an set viewport compositor to 'always'. Blender hangs (or is so slow, as to be indistinguisable from hanging on my machine). </details> <details> <summary>LLM Reasoning</summary> Got it, let's analyze the two bug reports. First, look at the description and steps. Bug Report 1: Focuses on rendering with denoise nodes in compositor causing hang/crash during compositing/finishing. Steps involve using Cycles, specific render settings, adding denoise nodes to passes, then rendering. Bug Report 2: About enabling real-time compositor (viewport compositing) when a denoise node is present, leading to hang. Steps are opening default scene, adding denoiser node, switching to rendered mode with viewport compositor always on. The key differences: Bug 1 is about render (final output) compositing during rendering process, while Bug 2 is about real-time (viewport) compositing when enabling it. The scenarios are different—render vs. viewport. So they're not the same issue. Therefore, answer is No. </details> <details> <summary>JSON Data</summary> { "llm_judgement": false, "processing_time": 13.606653999999999, "duplicate_report_number": "115156" } </details>

👍 1

Triager-bot commented

2026-04-12 17:21:14 +00:00

Report flagged as NOT a duplicate by LLM

GPU Compositing crashing Blender when working too quickly

https://projects.blender.org/blender/blender/issues/151204

System Information
Operating system: Windows-10-10.0.19045-SP0 64 Bits
Graphics card: NVIDIA GeForce RTX 3080 NVIDIA Corporation NVIDIA 581.57 Vulkan Backend

Blender Version
Broken: version: 5.1.0 Alpha, branch: main, commit date: 2025-12-04 01:11, hash: 746c83811bfd
Worked: 5.0.0, branch: blender-v5.0-release, commit date: 2025-11-18 09:54, hash: a37564c4df7a

Short description of error
In The Blender Compositor, using GPU Compositing, Blender will crash when working too quickly.

Exact steps for others to reproduce the error
I can not reliably reproduce the error, it only occurs when working so fast it causes freezing. In 5.0 it would recover now it always crashes. Using CPU Compositing instead of GPU fixed it for me.
my graphic drivers should also be up-to-date, and I run pretty stock clocks and setting.

I've gotten it to crash when bluing a large image by a many pixels. This takes more than 300ms reported on my system. Then I muted the Blur node o few time quickly so that it starts compositing and cancels it again. It crashed 3/5 time when muting and unmuting the node 3–4 times in a few seconds.

The glare: fog glow and displace Node all caused crashes.

3 crash reports I collected
blender.crash.txt
blender.crash1.txt
Grain node.crash.txt
this file crashes the most frequently when previewing inside of nodegorup and quickly entering or leaving those.
Grain shipped2 (2).blend

LLM Reasoning

Got it, let's analyze the two bug reports. First, look at the description and steps.

Bug Report 1: Focuses on rendering with denoise nodes in compositor causing hangs/crashes during compositing/finishing. Steps involve using Cycles, specific render settings, adding denoise nodes to passes, then rendering leads to hang/crash.

Bug Report 2: About GPU Compositing crashing when working too quickly (like muting/unmuting nodes fast, blur node on large image). Steps are about quick actions in compositor (blur, glare, etc.) causing crashes. The issue here is speed of interaction leading to crash, not rendering with denoise passes.

The core issues: Report 1 is rendering-related (denoise during render), Report 2 is interactive compositing (quick node operations). Different triggers and contexts. So they're not the same.

JSON Data

{
"llm_judgement": false,
"processing_time": 14.932684,
"duplicate_report_number": "151204"
}

### Report flagged as NOT a duplicate by LLM <details> <summary>GPU Compositing crashing Blender when working too quickly</summary> https://projects.blender.org/blender/blender/issues/151204 **System Information** Operating system: Windows-10-10.0.19045-SP0 64 Bits Graphics card: NVIDIA GeForce RTX 3080 NVIDIA Corporation NVIDIA 581.57 Vulkan Backend **Blender Version** Broken: version: 5.1.0 Alpha, branch: main, commit date: 2025-12-04 01:11, hash: `746c83811bfd` Worked: 5.0.0, branch: blender-v5.0-release, commit date: 2025-11-18 09:54, hash: `a37564c4df7a` **Short description of error** In The Blender Compositor, using GPU Compositing, Blender will crash when working too quickly. **Exact steps for others to reproduce the error** I can not reliably reproduce the error, it only occurs when working so fast it causes freezing. In 5.0 it would recover now it always crashes. Using CPU Compositing instead of GPU fixed it for me. my graphic drivers should also be up-to-date, and I run pretty stock clocks and setting. I've gotten it to crash when bluing a large image by a many pixels. This takes more than 300ms reported on my system. Then I muted the Blur node o few time quickly so that it starts compositing and cancels it again. It crashed 3/5 time when muting and unmuting the node 3–4 times in a few seconds. The glare: fog glow and displace Node all caused crashes. 3 crash reports I collected [blender.crash.txt](/attachments/7e556137-39a3-4c21-954b-899ade403a6d) [blender.crash1.txt](/attachments/cd3edef0-9b1f-438e-b51f-31eb7b6e878e) [Grain node.crash.txt](/attachments/457f6c4a-12ef-4f3b-920b-303ab70cb955) this file crashes the most frequently when previewing inside of nodegorup and quickly entering or leaving those. [Grain shipped2 (2).blend](/attachments/3d67ddcd-68a3-4109-80b0-6bcfee6868ae) </details> <details> <summary>LLM Reasoning</summary> Got it, let's analyze the two bug reports. First, look at the description and steps. Bug Report 1: Focuses on rendering with denoise nodes in compositor causing hangs/crashes during compositing/finishing. Steps involve using Cycles, specific render settings, adding denoise nodes to passes, then rendering leads to hang/crash. Bug Report 2: About GPU Compositing crashing when working too quickly (like muting/unmuting nodes fast, blur node on large image). Steps are about quick actions in compositor (blur, glare, etc.) causing crashes. The issue here is speed of interaction leading to crash, not rendering with denoise passes. The core issues: Report 1 is rendering-related (denoise during render), Report 2 is interactive compositing (quick node operations). Different triggers and contexts. So they're not the same. </details> <details> <summary>JSON Data</summary> { "llm_judgement": false, "processing_time": 14.932684, "duplicate_report_number": "151204" } </details>

👍 1

Triager-bot commented

2026-04-12 17:21:31 +00:00

Report flagged as NOT a duplicate by LLM

Compositor: Denoising EXR sequences accumulates memory with each frame

https://projects.blender.org/blender/blender/issues/151940

System Information
Operating system: Windows-10-10.0.26100-SP0 64 Bits
Graphics card: NVIDIA GeForce RTX 4090/PCIe/SSE2 NVIDIA Corporation 4.6.0 NVIDIA 581.80 Opengl Backend

Blender Version
Broken: version: 5.1.0 Alpha, branch: main, commit date: 2025-12-19 22:17, hash: 29afe701205d
Broken: 5.0
Broken: 4.5
Worked: Unsure

Short description of error
When using the compositor with a denoise node to denoise a EXR sequence, memory usage will climb with each frame rendered until you're out of memory and Blender crashes.

This issue was originally reported by @FhyTan in https://projects.blender.org/blender/blender/issues/137969#issuecomment-1797827

Exact steps for others to reproduce the error

Prepare a EXR sequence to denoise:
- Download and open EXR Generator.blend
- Render the animation with Render -> Render Animation
  - This will create a folder called EXRs that contains a 500 image sequence. You can increase or reduce the number of frames rendered.
Reproducing the issue:
- Download and open: Memory leak with denoise node compositor.blend This file was created by:
  - Opening the compositor
  - Importing the EXR sequence into the compositor
  - Connecting the relevant outputs of the EXR sequence to the denoise node which is then connected to the compositor output.
  - Change Render Properties -> Performance -> Compositor -> Denoise Nodes -> Denoising Device to GPU (This is not neccesary to reproduce the issue, but it does speed it up)
- Render the scene with Render -> Render Animation
- Notice that memory usage climbs with each frame rendered. In my case, ~80GB is consumed after 1500 frames has been processed.

LLM Reasoning

Got it, let's analyze these two bug reports. First, look at the descriptions and steps.

Bug report 1: The issue is Blender hanging or crashing during rendering when using denoise nodes on render passes in the compositor. Steps involve setting up Cycles with GPU compute, specific samples, film settings, adding file output and denoise nodes to diffuse direct and ambient occlusion passes, then rendering—hanging at compositing/finishing.

Bug report 2: The issue is memory accumulation when using denoise node on EXR sequences, leading to crash. Steps involve preparing an EXR sequence, importing into compositor with denoise node, rendering animation, memory climbs each frame until out of memory.

The core issues are different: one is hanging/crashing during compositing (maybe due to GPU or processing), the other is a memory leak from denoising EXR sequences. The steps and symptoms don't match. So they're not the same issue.

JSON Data

{
"llm_judgement": false,
"processing_time": 15.309958,
"duplicate_report_number": "151940"
}

### Report flagged as NOT a duplicate by LLM <details> <summary>Compositor: Denoising EXR sequences accumulates memory with each frame</summary> https://projects.blender.org/blender/blender/issues/151940 **System Information** Operating system: Windows-10-10.0.26100-SP0 64 Bits Graphics card: NVIDIA GeForce RTX 4090/PCIe/SSE2 NVIDIA Corporation 4.6.0 NVIDIA 581.80 Opengl Backend **Blender Version** Broken: version: 5.1.0 Alpha, branch: main, commit date: 2025-12-19 22:17, hash: `29afe701205d` Broken: 5.0 Broken: 4.5 Worked: Unsure **Short description of error** When using the compositor with a denoise node to denoise a EXR sequence, memory usage will climb with each frame rendered until you're out of memory and Blender crashes. This issue was originally reported by @FhyTan in https://projects.blender.org/blender/blender/issues/137969#issuecomment-1797827 **Exact steps for others to reproduce the error** - Prepare a EXR sequence to denoise: - Download and open [EXR Generator.blend](/attachments/2f8ce951-a688-4a10-ad8d-51341c9081f0) - Render the animation with `Render -> Render Animation` - This will create a folder called `EXRs` that contains a 500 image sequence. You can increase or reduce the number of frames rendered. - Reproducing the issue: - Download and open: [Memory leak with denoise node compositor.blend](/attachments/c680d018-ad5f-4a6f-a5b1-e9ec34d911c5) This file was created by: - Opening the compositor - Importing the EXR sequence into the compositor - Connecting the relevant outputs of the EXR sequence to the denoise node which is then connected to the compositor output. - Change `Render Properties -> Performance -> Compositor -> Denoise Nodes -> Denoising Device` to `GPU` (This is not neccesary to reproduce the issue, but it does speed it up) - Render the scene with `Render -> Render Animation` - Notice that memory usage climbs with each frame rendered. In my case, ~80GB is consumed after 1500 frames has been processed. </details> <details> <summary>LLM Reasoning</summary> Got it, let's analyze these two bug reports. First, look at the descriptions and steps. Bug report 1: The issue is Blender hanging or crashing during rendering when using denoise nodes on render passes in the compositor. Steps involve setting up Cycles with GPU compute, specific samples, film settings, adding file output and denoise nodes to diffuse direct and ambient occlusion passes, then rendering—hanging at compositing/finishing. Bug report 2: The issue is memory accumulation when using denoise node on EXR sequences, leading to crash. Steps involve preparing an EXR sequence, importing into compositor with denoise node, rendering animation, memory climbs each frame until out of memory. The core issues are different: one is hanging/crashing during compositing (maybe due to GPU or processing), the other is a memory leak from denoising EXR sequences. The steps and symptoms don't match. So they're not the same issue. </details> <details> <summary>JSON Data</summary> { "llm_judgement": false, "processing_time": 15.309958, "duplicate_report_number": "151940" } </details>

👍 1

Triager-bot commented

2026-04-12 17:21:46 +00:00

Report flagged as NOT a duplicate by LLM

Compositor Denoise super slow while rendering

https://projects.blender.org/blender/blender/issues/129966

System Information
Operating system: Windows
Graphics card: RTX 3070

Blender Version
Broken: 4.2.0, main,
Worked: Non

The compositor denoise is super slow while rendering for multi pass data.

Exact steps for others to reproduce the error
Press render and see with the denoise nodes and then with and there's a huge difference, is there any way we could have GPU acceleration on these nodes? Thank you

LLM Reasoning

Got it, let's analyze the two bug reports. First, look at the description and steps to reproduce.

Bug report 1: Focuses on Blender 5.1.0 hanging or crashing during rendering when using denoise nodes on render passes in compositor. Steps involve specific settings (Cycles, GPU Compute, Optix Denoise, certain passes, adding denoise nodes) leading to hang/crash at compositing/finishing.

Bug report 2: Talks about compositor denoise being super slow while rendering multi-pass data. Steps are vague ("Press render and see with the denoise nodes...") but mentions wanting GPU acceleration.

The key differences: Bug 1 is about hanging/crashing (a crash/hang issue), Bug 2 is about slowness (performance). Even though both involve denoise in compositor, the symptoms (hang vs slow) are different. Also, steps to reproduce differ—Bug 1 has detailed steps with specific settings, Bug 2 is vague. So they're not the same issue.

JSON Data

{
"llm_judgement": false,
"processing_time": 14.428653,
"duplicate_report_number": "129966"
}

### Report flagged as NOT a duplicate by LLM <details> <summary>Compositor Denoise super slow while rendering</summary> https://projects.blender.org/blender/blender/issues/129966 **System Information** Operating system: Windows Graphics card: RTX 3070 **Blender Version** Broken: 4.2.0, main, Worked: Non The compositor denoise is super slow while rendering for multi pass data. **Exact steps for others to reproduce the error** Press render and see with the denoise nodes and then with and there's a huge difference, is there any way we could have GPU acceleration on these nodes? Thank you </details> <details> <summary>LLM Reasoning</summary> Got it, let's analyze the two bug reports. First, look at the description and steps to reproduce. Bug report 1: Focuses on Blender 5.1.0 hanging or crashing during rendering when using denoise nodes on render passes in compositor. Steps involve specific settings (Cycles, GPU Compute, Optix Denoise, certain passes, adding denoise nodes) leading to hang/crash at compositing/finishing. Bug report 2: Talks about compositor denoise being super slow while rendering multi-pass data. Steps are vague ("Press render and see with the denoise nodes...") but mentions wanting GPU acceleration. The key differences: Bug 1 is about hanging/crashing (a crash/hang issue), Bug 2 is about slowness (performance). Even though both involve denoise in compositor, the symptoms (hang vs slow) are different. Also, steps to reproduce differ—Bug 1 has detailed steps with specific settings, Bug 2 is vague. So they're not the same issue. </details> <details> <summary>JSON Data</summary> { "llm_judgement": false, "processing_time": 14.428653, "duplicate_report_number": "129966" } </details>

👍 1

Triager-bot commented

2026-04-12 17:22:00 +00:00

Report flagged as NOT a duplicate by LLM

Compositor alpha over crashing Blender 5.1 high res output

https://projects.blender.org/blender/blender/issues/156830

System Information
Operating system: Windows-11-10.0.26200-SP0 64 Bits
Graphics card: NVIDIA GeForce RTX 4070/PCIe/SSE2 NVIDIA Corporation 4.6.0 NVIDIA 595.79 Opengl Backend

Blender Version
Broken: version: 5.1.0, branch: blender-v5.1-release, commit date: 2026-03-16 18:50, hash: adfe2921d5f3
Worked: (version 5.0.1)

Short description of error
When using World Background as Transparent and Alpha Over in Compositor, Blender crashes (Cycles)

Exact steps for others to reproduce the error

enable Optix in Cycles Render Devices;
set Render Engine as Cycles;
use GPU in Device, Denoise and Compositor;
set Render Max Samples to 64 (just to make it faster);
enable Transparent in Film Render Properties;
add Alpha Over node in Compositor Nodes;
render Default Cube with default resolution (it works fine);
increase Format Resolution % to 450;
- Here's a file setup to this point.
Blender crashes after rendering denoising (see video).

LLM Reasoning

Got it, let's analyze the two bug reports. First, look at the description and steps.

Bug report 1: Hangs or crashes during compositing/finishing when using denoise nodes on render passes (Diffuse Direct, Ambient Occlusion) with GPU compositor, specific resolution (4096x2304), Optix denoise.

Bug report 2: Crashes when using Alpha Over node in compositor with transparent background, high res (450% format resolution), Optix enabled. The steps involve Alpha Over, not denoise nodes on passes like the first one.

The key differences are the specific nodes used (denoise vs Alpha Over) and the context of render passes vs Alpha Over. So they're different issues. Therefore, the answer is No.

JSON Data

{
"llm_judgement": false,
"processing_time": 12.472591,
"duplicate_report_number": "156830"
}

### Report flagged as NOT a duplicate by LLM <details> <summary>Compositor alpha over crashing Blender 5.1 high res output</summary> https://projects.blender.org/blender/blender/issues/156830 **System Information** Operating system: Windows-11-10.0.26200-SP0 64 Bits Graphics card: NVIDIA GeForce RTX 4070/PCIe/SSE2 NVIDIA Corporation 4.6.0 NVIDIA 595.79 Opengl Backend **Blender Version** Broken: version: 5.1.0, branch: blender-v5.1-release, commit date: 2026-03-16 18:50, hash: `adfe2921d5f3` Worked: (version 5.0.1) **Short description of error** When using World Background as Transparent and Alpha Over in Compositor, Blender crashes (Cycles) **Exact steps for others to reproduce the error** - enable Optix in Cycles Render Devices; - set Render Engine as Cycles; - use GPU in Device, Denoise and Compositor; - set Render Max Samples to 64 (just to make it faster); - enable Transparent in Film Render Properties; - add Alpha Over node in Compositor Nodes; - render Default Cube with default resolution (it works fine); - increase Format Resolution % to 450; - Here's a file setup to this point. - Blender crashes after rendering denoising (see video). </details> <details> <summary>LLM Reasoning</summary> Got it, let's analyze the two bug reports. First, look at the description and steps. Bug report 1: Hangs or crashes during compositing/finishing when using denoise nodes on render passes (Diffuse Direct, Ambient Occlusion) with GPU compositor, specific resolution (4096x2304), Optix denoise. Bug report 2: Crashes when using Alpha Over node in compositor with transparent background, high res (450% format resolution), Optix enabled. The steps involve Alpha Over, not denoise nodes on passes like the first one. The key differences are the specific nodes used (denoise vs Alpha Over) and the context of render passes vs Alpha Over. So they're different issues. Therefore, the answer is No. </details> <details> <summary>JSON Data</summary> { "llm_judgement": false, "processing_time": 12.472591, "duplicate_report_number": "156830" } </details>

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