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Rendering with Arnold in CINEMA 4D using the C4DtoA plug-in.
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ai.dll plugin keeps crashing

Message 1 of 12
1645 Views, 11 Replies

ai.dll plugin keeps crashing

IPR works fine - as soon as I send it to picture viewer, the second frame crashes, and I get a pop-up with the message 'ai.dll has crashed', then c4d closes.

I've uninstalled and reinstalled Arnold twice. It's not just one scene either; my current project is quite heavy and won't get past frame two. I ran an older project out of curiosity. It was a straightforward scene to understand further if it's something in my current workflow that's triggering the crash - it wouldn't get past frame 24; I tried to render four times, and the same issue always occurred, always on frame 24.

Why would this be happening? I'm trying to figure it out, and I can't seem to find anything online. It doesn't seem to be a common issue. I came across one thread on this forum; the person who asked the question said turning off Auto tx fixed the issue for him. I tried, and that didn't work either.

I'm rendering with two RTX 3090s.

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Message 2 of 12

What about using the Render Queue, or command-line rendering? Do they crash too?

Can you get an Arnold log, so we can see what versions you use and what device (CPU/GPU) ?

// Stephen Blair
// Arnold Renderer Support
Message 3 of 12

Hi @Stephen Blair

Thank you for your reply!

I'm sorry to be a pain - how do I retrieve the log after C4D crashes/closes?

Message 4 of 12


I'm using two RTX 3090s, the latest drivers and the latest version of Arnold.

Message 5 of 12

You can enable File logging:
Put arnold.####.log to get frame numbers in the log file name.

// Stephen Blair
// Arnold Renderer Support
Message 6 of 12

It seems like it's memory. I didn't think memory would have been an issue; I have maybe four complex shaders and 48GB VRAM. Also, forgive my ignorance, but how can it render frame one fine but then fail on frame two? Does each frame not use the same amount of VRAM?

It won't let me upload txt doc so I had to screenshotscreenshot-2021-12-22-135616.png

Message 7 of 12

If you give the log file a .txt extension (eg arnold.0001.log.txt) you should be able to upload that. I do that.

How much free VRAM was detected before the first, successful frame render?

The screenshot shows that over half the VRAM was already in use when the second frame started.

What this Render to Picture Viewer or Render Queue?

// Stephen Blair
// Arnold Renderer Support
Message 8 of 12

That's the entirety of the log. I have a very dense ground layer with displacement layers; could that be the culprit of half my Vram missing?

But when I run the IPR, it peaks at around 17,000Mb and never any higher, I can quite quickly move around in the scene, and it doesn't crash. I've attached a screenshot of the IPR view/Log if that helps...

Thanks again for responding; I'm at a loss. I don't know too much about the technicalities of rendering.


Message 9 of 12

Hi Chris

If you set the Arnold log verbosity to Info, we'll get more info. Like how much GPU memory a successful render takes. You can set the log verbosity on the Arnold Render Settings > Diagnostics tab.

Extensions > Console:


// Stephen Blair
// Arnold Renderer Support
Message 10 of 12

I'm curious what is using all the GPU memory. You have 48GB but when the render starts, there's just about 20GB free.

Is it just CINEMA 4D and the Picture Viewer that uses up all the rest? I would try with Render Queue (and no Picture Viewer) or command-line rendering:

// Stephen Blair
// Arnold Renderer Support
Message 11 of 12


I've attached the log; it won't even render the first frame now.

It seems like It's started with less than half of my available ram, but I don't understand why? Is there a way to change a setting to utilise all available ram?

Message 12 of 12

I think I've figured it out. I had a sculpt tag on my floor to do some manual displacement, to break up the pattern/tiling. I was rendering straight out with the tag still on, once I removed that it rendered fine. It started the render only using 4gb vram instead of 20gb. So it was either the tag itself, or the high subdivision the tag was creating for me to sculpt.

I need to find a better way to subdivide large scale areas like floors for displacement. I'm still learning, I don't understand how people have crazy detailed floors without killing their vram.

Thank you for your time

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