Why Does Blender Crash While 3D Modeling?


Depending on your projects you may sometimes find that while working on a model Blender decides to close for no reason. At other times it may end up loading your scene forever and you then need to close Blender yourself. There are few things more frustrating than Blender crashing in the middle of a project.

The main reason why Blender crashes while modeling is because there is too much geometry in the scene for your hardware to compute. Examples of when this can occur include tools that add geometry like the subdivision surface modifier or when you try to move about too quickly in a heavily dense scene and your device can’t keep up.

It is very easy to create a scenario where Blender becomes unresponsive and even decides to close all on its own. What are the scenarios where crashing is most likely to occur and more importantly how can we prevent this or restore our lost work?

When Is Blender Most Likely To Crash While Modeling?

Any program has the potential to crash when a tool is used, and Blender has more tools than most other applications that you are likely to use. The most common task that Blender is used for is to create 3D objects and scenes, and so this is also the aspect of Blender where you are most likely to experience a slowdown, freezing, and crashing.

Your computer has to calculate the various aspects of your 3D scene in real-time so that you can edit the scene in real-time using the many editing tools.

Slowdown is the most common issue that you are likely to come across if your hardware is not up to scratch and is visibly seen as laggy performance when you are attempting to navigate around your 3D viewport. This is likely to occur after you add a significant amount of geometry to your scene like with the subdivision surface modifier.

The phenomenon of viewport slowdown is more common when single objects have a lot of geometry compared to more objects that have less dense geometry per model. As such, an area of modeling where you are also likely to experience slowdown is sculpting, where the dynamic topology is often used to add geometric detail in real-time.

Freezing is the scenario where Blender is attempting to load something and that loading process is taking far longer than it is expected to. When Blender freezes, the entire interface is greyed out while Blender attempts to load the scene, and all tools become inaccessible while Blender loads the previous action.

Times when freezing is common include when you use particle systems in your scenes like applying hair to character models, and when adding too much geometry to single objects. It is not the same as a typical slowdown, where the scene impacts the performance and is more a case of a tool requiring more processing time to complete.

Sometimes though Blender never comes out of this and is stuck in a loop, resulting in you having to close Blender. Whenever you see Blender freeze up wait a minimum of 30 seconds for it to unfreeze. If it goes past 30 seconds then it will likely not restore and you will need to close.

Crashing is the worst-case scenario for any Blender artist because it means a potential loss of work. A crash can appear in one of two ways. When your project has frozen a command prompt may appear where you are asked to either wait for Blender to complete whatever tool it is trying to process, or you can close Blender.

While the prompt gives you the option, seeing it usually means that Blender has crashed and that you will need to close and restart the software.

The second scenario is where Blender just closes for no apparent reason. No command prompt and no warning, Blender can at times just close down. The causes for both slowdown and freezing can also cause Blender to crash, but another reason as to why this happens is when certain tools are used when they perhaps should not be used.

This is not common, as all tools should work together, but using tools in certain combinations may confuse Blender with what you are trying to do, and if it’s not sure, it might just decide to close.

If there are any bugs that are connected to specific tools, then these bugs can also cause Blender to crash. For example, while using Blender version 2.93 I found that Blender would crash and close if I ever tried to use the undo tool while working with geometry nodes.

What Hardware Is Recommended For The More Computationally Heavy Tasks?

Newer versions of Blender are better optimized and so you can work with more geometry, lighting, and complex materials than you could before using the same hardware. However, there is always going to be a limit until Blender comes up with its own version of the nanite system used in Unreal engine 5 of course.

For most setups, you will be fine with scenes that have fave counts even going up to the hundreds of thousands, but once you pass that one million mark, then you enter risky territories.

Let’s use my setup as a baseline, for which I use an intel i7 8700 as my CPU and an Nvidia GTX 1070 as my GPU, 16GB of 2166hz memory, and a 1TB SSD for storage space.

With scene creation, I will experience a slowdown at around the 2.2 million mark for the face count. With sculpting, where the geometry is tightly packed into a single object, slowdown begins to occur at a little over half that number, at 1.4 million.

These numbers can differ even using the same hardware depending on the scene, however, so keep that in mind. I recommend the above specs as a minimum if you are interested in creating realistic scenes and high poly sculpts using Blender.

For instances where crashing occurs from using a specific tool, this is more likely a bug on Blenders side and therefore the hardware that you use is irrelevant.

How Can I Improve My Viewport Performance When Using A Lot Of Geometry?

If you are working on a project that requires you to work on a scene with dense geometry then you may not want to invest heavily in new hardware and would prefer a quick and easy solution. So we have a couple of tips for what you can do to improve your viewport performance.

In the case that your objects are using the subdivision surface modifier, you will have two objects with the modifier, viewport and render levels. With this, you can set the viewport level down to a low number like 1 so that you can visualize the shape of the object in the viewport while working without it affecting performance too much.

Set the render value to a higher number like 4 to get the best detail in your actual render. This way you can ensure that your objects are not impeding performance while you are still modeling them.

Another incredibly useful tool when building up scenes is the local view tool. By default, we work in the global view, where the entire scene is visible. By going into local view we can isolate the scene to the selected model. Press the / key on your keyboard to toggle the local view for your selection and you will be able to focus on that object only. Use the same key to return to the global view.

Alternatively, you can choose to hide any objects that you are not working on in the viewport by selecting them and pressing the H key. To restore hidden objects press the hotkey Alt + H.

Restoring Lost Work And Using The Autosave Feature

In the worst-case scenario, Blender crashes outright and the last time that you saved your work was about 30 minutes ago. When you open up Blender next time you will find the option labeled ‘restore previous session‘ on the splash screen.

This will attempt to load your project in Blender at the point just before it crashed. This is an invaluable tool but only works if you access Blender again without turning off your system in between sessions.

While you are working Blender will look to periodically save your project to a temporary cache file after each time that you use a tool. This cache file is emptied when you close down your computer, so the saved data gets wiped when your machine shuts down.

You can also enable the autosave feature itself, which saves the project at user-defined intervals. Go to the edit menu at the top of the UI, and select preferences, where a new window will pop up. Go to the section labeled Save And Load and tick the box for autosave.

You have one other option here, and that’s to control how frequently your autosave is used. The default value of 2 minutes is good enough, but change it to the time you want or are comfortable with, then close the preferences panel.

Note that the autosave feature only works if you have already saved your project at least once.

Thanks For Reading The Article

That’s it for this article, and we hope it was able to provide you with what you were looking for. Below you will find a small list of additional topics that you may be interested in reading through.

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