Unhandled Exception (no error code) only on certain frames of animation

[uforis]

Hi there.

I'm getting some weird unhandled exception errors on 1 or 2 frames of animation. I can't really understand why this could be happening, as in a 96 frame clip, most frames render perfectly fine, with one or two absolutely refusing to render. The scenes I have aren't crazy award winning stuff, just some simple interiors without much going on at all.

I've tried several optimizations as well, using 8 bit textures with mip maps, or even resizing them as low as 512, and I still get an unhandled exception. On these frames, switching to bucket mode, just crashes Max as well, but only on these frames.

I am render with GPU Progressive, Brute Force Secondary GI with 4 subdivs. I know the recommended settings are to use lightcache 3000 subdivs with 8 retrace, but I have seen flickering with those settings so taking a risk on using the is a huge pain.

Any ideas?

[yavor.rubenov]

Hello,

When Max crashes it should write a crash dump called 3dsmax_minidump.dmp in your temp folder (type %temp% in windows explorer address bar). Could you attach it here or send it to support. Also if there's a vray.dmp file - attach it here too.
Additionally - if you can send the scene to support too it would also be very helpful.

Best regards,
Yavor

[uforis]

Hi yavor,

Here's a link to the crash dump.

I don't think I'm going to have time to package up and send you my project. If you can give me some general guidance in things to look out for regarding mitigating crashes when using GPU rendering that would really help, as I'm in a bit of a crunch.

Again, it's just specific frames just continue to crash no matter what I do.

[yavor.rubenov]

Thanks for the dump. Few things we noticed:
- You are using V-Ray version 4.20.01.00001. Ideally - could you update to V-Ray 4.3 ? If that is not an option - we had some minor fixes for V-Ray 4.20 - on our site you can download the newer version V-Ray 4.20.01.00002.
- Seems you are using Hybrid rendering (the crash happens in the CUDA/C++ codepath). It's a long shot but could you try to use just the GPUs for the problem frame ?
- The crash happens in parts of the code related to light include/exclude lists but unfortunately we can't say which light exactly.

One other thing to try if you could - enable DR for that render but use only local host. In that case we start V-Ray Standalone and the rendering happens in it. When the crash happens - it should generate dump called vray.dmp in the temp folder and it can contain a bit more information.

[uforis]

Hi Yavor, I'll try all of those things and report back. The strangest thing is that the problem frames exist in multiple scenes, but on the same exact frames (33, 45). A haunting coincidence I hope :/

The crashes happen on specific buckets btw, not sure if that matters.

[uforis]

Any insight as to why most of the frames would render totally fine but crash on very specific frames?

[uforis]

Well Yavor good sir, it seems that your longshot did the trick. The Hybrid rendering was causing the crash on these frames. If you have any more insight into what's going on with the Hybrid I'd appreciate learning more about it from a technical point of view.

When I'm done this project I'm going to upgrade to the newest version, I didn't want to change mid-project.

Thanks Yavor!

[yavor.rubenov]

Glad that it worked out.
GPUs can some times hide bugs - internally they initialize everything in memory to zero initially. On the CPU this doesn't happen so if something is left uninitialized (due to a bug) - we can get random values that can cause crashes.
Ideally when you have some more time - send us the project so that we check what is actually going on.