Blender 5.1 freezes on startup (black screen, Application Hang, infinite depsgraph loop, Windows 11) #61
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Reference: Triager-bot/blender-bug-reports#61
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Original bug report: https://projects.blender.org/blender/blender/issues/157250
System Information
Operating system: Windows 11 Pro (64-bit) (Build 26200.8037)
Graphics card: AMD Radeon RX 5600 XT
Driver version: 26.3.1.260303
Blender version: 5.1.0 (hash adfe2921d5f3)
Working Version
Blender 5.0 LTS works normally.
Problem
Blender 5.1 freezes immediately on startup.
The window remains completely black and becomes unresponsive.
Windows reports an "Application Hang" (Event ID 1002).
No crash dialog or error message is shown.
I tested the daily versions 5.1.1 and 5.2.0 and they are also experiencing errors.
Steps to Reproduce
Observed Behavior
Tests Performed
The issue persists under all of the following conditions:
Debug Findings
Blender appears to enter an infinite loop in dependency graph updates:
DEG_relations_tag_update: Tagging relations for update.
graph_id_tag_update: id=SCScene ...
graph_id_tag_update: id=GRScene Collection ...
graph_id_tag_update: id=GRCollection ...
This repeats indefinitely.
Thread Stack (Process Explorer)
The active thread shows Python execution involving WMI:
_wmi.pyd
python313.dll
blender.exe
The module _wmi.pyd is loaded from:
Blender 5.1\5.1\python\DLLs
ProcMon Observations
Additional Notes
Expected Behavior
Blender should start normally and display the default UI.
Regression
Yes (Blender 5.0 works, Blender 5.1 does not)
Attachments
(attach logs and stack traces if available)
Report is clear
LLM Reasoning
Got it, let's see. The question is whether the bug report clearly describes the issue. I need to check if the description and steps are clear.
First, the title says Blender 5.1 freezes on startup. The body explains that it freezes immediately with a black screen, Windows reports an Application Hang. Steps to reproduce are simple: launch Blender 5.1, observe black window, freeze. They also mention tests done (like factory-startup, background mode) which show they tried different scenarios. Debug findings include the infinite loop in dependency graph and WMI-related Python execution.
The steps are clear: 1. Launch, 2. Observe black screen, 3. Freeze. The problem is well-described with symptoms (black window, unresponsive, Application Hang). They also mention regression from 5.0 to 5.1. So the clarity of the text and steps seems good. No major issues here. So the answer should be Yes.
JSON Data
{
"llm_judgement": true,
"processing_time": 14.034801999999999
}
Report is specific
LLM Reasoning
Got it, let's figure out if this bug report is specific or generic. The user wants a single word: 'Specific' or 'Generic'.
First, let's recall the definitions. Specific bug reports are about a particular issue, like crashing while using a specific feature. Generic ones are vague, like "crashing while rendering" without details.
Looking at the report: The title mentions Blender 5.1 freezing on startup (black screen, infinite depsgraph loop). The body has steps to reproduce (launch Blender 5.1, observe black window), debug findings about an infinite loop in dependency graph updates, thread stack with WMI, etc. It's not a vague issue; it's a specific problem with Blender 5.1 startup freezing due to an infinite depsgraph loop. Also, it compares to working version (5.0 LTS) and mentions regression. So this is a specific issue because it's about a particular scenario (startup freeze in 5.1) with detailed steps and debug info.
So the answer should be 'Specific'.
JSON Data
{
"llm_judgement": true,
"processing_time": 15.200843
}
Report flagged as NOT a duplicate by LLM
Viewport freezing
https://projects.blender.org/blender/blender/issues/153212
System Information
Operating system: Windows 11 pro
Graphics card: RTX 5070ti
Blender Version
Broken: 5.01
Worked:
Short description of error
Sometimes Blender goes into a kind of loop of freezing. Ive noticed that the GPU usage goes to 100% and down to 0% repeatetly for minutes, like up to 40 minutes (that was the most I could wait before shutting down blender) but sometimes the waiting is shorter. Its just impossible to work while this happens. I cant save or do anything. Blender still running but frozzen. Its not the processor but the GPU, as I show on the screen shot. Most of the times this happened was selecting a link collection, or framing the zoom on it. The collection is fine, nothing heavy to manage or something. Just simple objects.
*Exact steps for others to reproduce the error
Although it’s constantly happening, still random so I can`t intentionally reproduce the problem. When this happens the process is the same, its like a GPU loop of freezing.
LLM Reasoning
Got it, let's analyze these two bug reports. First, look at the key sections: Description and Steps to Reproduce.
Bug Report 1: Freezes on startup (black screen, infinite depsgraph loop). The steps are launching Blender 5.1 and observing a black window that hangs. The issue is immediate startup freeze with an infinite loop in dependency graph.
Bug Report 2: Viewport freezing, GPU usage looping (100% to 0%). Steps mention it's random, happens when selecting link collection or framing zoom. The problem is viewport-related, not startup, and involves GPU usage cycles, not a depsgraph loop.
So the core issues are different: one is startup freeze with depsgraph loop, the other is viewport freezing with GPU loops during use. Therefore, they're not the same issue.
JSON Data
{
"llm_judgement": false,
"processing_time": 13.643339,
"duplicate_report_number": "153212"
}
Report flagged as NOT a duplicate by LLM
3.5.1 installation hangs on Windows 10
https://projects.blender.org/blender/blender/issues/107352
System Information
Operating system: Windows-10-10.0.19045-SP0 64 Bits
Graphics card: NVIDIA GeForce GTX 1650/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 516.94
Blender Version
Broken: version: 3.5.1, branch: blender-v3.4-release, commit date: 2022-12-19 17:00, hash:
rB55485cb379f7Worked: 3.4.1
Short description of error
3.5.1 installation hangs on Windows 10
Exact steps for others to reproduce the error
This never happened to me with Blender before... I wanted to test 3.5.1 so I downloaded "blender-3.5.1-windows-x64.msi", started installing it alongside 3.4.1 and the process simply hanged and has been like this for the past hour. I was only able to kill it from within the task manager. What gives???
LLM Reasoning
Got it, let's analyze these two bug reports. First, look at the key sections: description and steps to reproduce.
Bug report 1 is about Blender 5.1 freezing on startup (black screen) on Windows 11, with an infinite depsgraph loop. The steps are launching Blender 5.1 and observing it freeze.
Bug report 2 is about Blender 3.5.1 installation hanging on Windows 10 during the install process, not startup. The steps are installing via MSI and the installer hanging.
The issues are different: one is a runtime freeze on startup (after launching), the other is an installation hang (during setup). So they're not the same issue. Therefore, the answer is No.
JSON Data
{
"llm_judgement": false,
"processing_time": 12.990162,
"duplicate_report_number": "107352"
}
Encountered error when checking if these reports were duplicates.
Blender 4.5.1 crashing on startup
https://projects.blender.org/blender/blender/issues/{duplicate_report_number}
{duplicate_report_data['body']}
Report flagged as NOT a duplicate by LLM
Blender 5.0.1 - Windows 11 freezing issue?
https://projects.blender.org/blender/blender/issues/155219
System Information
Blender Version
Short description of error
Blender 5.0 suffers from frequent UI freezes (1-2 seconds) even in an empty scene or when interacting with menus. This issue occurs on my system with hybrid graphics (Intel + NVIDIA RTX) and an external monitor connected, and only in Blender 5.0. Blender 4.3 functions correctly without these freezes on the same hardware and OS. Can it be caused by the Addons update? (I recently updated all my addons with the latest compatible release on both get extension and the traditional Blender addon windows). // The issue seems to be fixed when I remove the startup files and load the factory settings, then open and close Blender again //
Exact steps for others to reproduce the error
Open Blender 5.0
Interact with any UI element, such as:
Notice the 1-2 second freeze in the UI, happening throughout the software. This freeze happens even without any complex scene loaded.
Additional information
Let me know if you need any more details or adjustments!
LLM Reasoning
Got it, let's analyze these two bug reports. First, look at the key sections: Description and Steps to Reproduce.
Bug Report 1: Freezes on startup (black screen, infinite loop), happens every time when launching Blender 5.1. The steps are launch Blender 5.1, observe black window, freeze. It's a complete hang with no UI rendering, infinite depsgraph loop.
Bug Report 2: Frequent UI freezes (1-2 seconds) when interacting with UI elements in Blender 5.0.1, not on startup but during use. Steps involve opening Blender 5.0 and interacting with UI (orbiting, hovering menus). The issue is intermittent freezes during interaction, not a complete hang on startup.
So the core issues are different: one is a startup freeze with infinite loop, the other is intermittent UI freezes during use. The descriptions and steps don't match. So they're not duplicates.
JSON Data
{
"llm_judgement": false,
"processing_time": 16.943838,
"duplicate_report_number": "155219"
}
Report flagged as NOT a duplicate by LLM
Freeze on startup on older NVIDIA GPUs after windows Jan 2026 update
https://projects.blender.org/blender/blender/issues/154308
System Information
Operating system: Windows 11 64-bit (fully updated as of 12.02.25). CPU: Intel 13900K, RAM: 128 GB
Graphics card: NVIDIA Quadro M2000, NVIDIA driver 582.08
Dxdiag reports Driver version 32.0.15.8208
Blender Version
Broken: 5.0.1.0 (Microsoft Store version)
Worked: 4.2.x (Microsoft Store version), 5.0.1 portable (Win32 ZIP from blender.org)
Short description of error
Starting Blender 5.0.1.0 installed via Microsoft Store causes a full system freeze on launch.
The freeze occurs immediately after Blender startup. No Blender UI element is shown. I may move the cursor but as soon as I click anywhere on screen, the video output freezes fully. Only recovery is holding down the power button for some seconds.
The issue does not occur with:
Blender 4.2.x installed via Microsoft Store
Blender 5.0.1 portable (Win32, non-Store)
This suggests a regression in Blender 5.0 combined with the Microsoft Store (UWP/Desktop Bridge) packaging and NVIDIA OpenGL initialization on Quadro M2000.
Exact steps for others to reproduce the error
Use a Windows system with NVIDIA Quadro M2000 GPU
Install Blender 5.0.1 from the Microsoft Store
Launch Blender 5.0.1 from the Start Menu
Result:
System freezes after a couple of seconds during Blender startup. Task bar shows blender application without icon. No window shown at all. No splash screen. No crash log in event manager.
Mouse cursor stops responding after a few seconds. System locked, no keyboard input or mouse input changes anything.
No crash dialog.
Hard reset via power button required.
Crash tested at least 5 times over the span of one week.
LLM Reasoning
Got it, let's analyze these two bug reports. First, look at the key sections: description and steps to reproduce.
Bug report 1 is about Blender 5.1 freezing on startup with a black screen, infinite depsgraph loop, on Windows 11 with AMD GPU. Steps are launching Blender 5.1, observing black window, freeze.
Bug report 2 is about Blender 5.0.1 (Microsoft Store) freezing on startup with NVIDIA Quadro M2000 after Windows update. Steps are installing from Microsoft Store and launching, leading to system freeze.
The issues have different causes: one is AMD GPU + depsgraph loop in 5.1, the other is NVIDIA Quadro + Microsoft Store version in 5.0.1. The symptoms (freeze on startup) might seem similar, but the root causes are different—different GPUs, different Blender versions, different installation methods. So they're not the same issue.
JSON Data
{
"llm_judgement": false,
"processing_time": 17.030859,
"duplicate_report_number": "154308"
}