Crash - but only after rendering

[pokoy]

Max 2016, SP1, Corona 1.2.1

So I have this particular scene where I can do everything with it, model, orbit around, enable/disable layers, view and edit materials etc. and it works fine.
If I render anything, even only a single object and cancel the render, Max will crash after some time (5-10 seconds) or when trying to orbit in the viewport, switch viewports etc.
It's 100% reproducible and really happens only after rendering with Corona.

I can't share the file but I am attaching the minidump, it may give you (and me) some pointers as to what exactly happens here and why...

[Ondra]

is there a displacement/camera mod on any object in the scene?

[pokoy]

I am trying the obvious solutions but at no avail.

- render with scanline to test scene stability - no crashes, Max remains stable
- rendering with Corona, latest daily (2015-09-06) - crash
- merging everything into a new scene and rendering with Corona - crash

I'm now looking for materials or maps that might cause this. It's a huge scene with tons of literally everything so having an idea what the minidump says would be great, if it include any useful info.

[pokoy]

is there a displacement/camera mod on any object in the scene?

No displacement, but I do use Camera modifiers.

[pokoy]

I deleted all CameraMods - no change, still getting the crashes.

It got a bit better with the merged file (well, it will take longer until max crashes...) but it crashes reproducibly if I change the viewport lighting mode from Shaded to Realistic. Seems like it's the viewport that crashes it, but why ONLY with Corona, and only AFTER a canceled render, not before?

The scene used to work perfectly with Corona before, I was working on it on-and-off for some time with various dailies and final versions, but the crashes seems to occur only since 1.2, there was not a single problem before and now it's 100% reproducible.

The only change that I made to some materials was that I'm using Shell materials on some objects to switch between two versions. However, these objects are not visible in the viewport nor in the rendering when the crashes occur.

Attached is another minidump from the viewport mode switch attempt, no clue if it makes sense to upload it, just in case.

[Ondra]

ok, I see in the minidump that it happens in a modifier that is being evaluated when light list is being updated. Can you post the scene? Is any of the lights in the scene somehow linked to any object, or has any modifier? Can you try if it crashes when you delete lights? Or can you upload just the lights from the scene (or full scene, your choice ;))

[pokoy]

The funny thing is there is no light in the scene, it's lit by a bitmap. In my tests it crashed without a light being present in the scene. And it definitely crashes everytime the viewport has to respond to user action, such as changing viewport style, or even clicking on the viewport label, all these actions will crash max.

I just tried merging bit-by-bit, here my results:

- merging single objects works, no crash
- merging a number of objects works fine, no crash
- merging the whole model (some thousands of objects) - crash on all the actions listed above

I don't get it. I'm currently trying in Max 2014 to find out if it's only happening in 2016.

Actually, considering how urgent I need this to be resolved, I am considering uploading the file... It's huge with tons on materials and maps, 3rd party map plugins required. Since isolating the issue is pretty hard I'm not sure if you'd really want such a massive file on the table. Let me know. I can try to strip down the scene.

[pokoy]

WAIT! There are 4 Corona Lights in the scene (set to off), totally forgot about them. Will isolate them and see if I can reproduce the issue.

[pokoy]

Unfortunately, deleting the lights didn't help. I am attaching a minidump from a crash without a light being present in the scene. Can you tell me if it's still related to lights?

Regarding the modifier attempting to update the light list... Which one could that be? Do object/material lights count?

[Ondra]

ok, this one was a bit different. This crash was initiated by testing whether an object is a camera after a menu action was invoked. Which caused evaluation of an object, and this evaluation crashes.

I have no idea which object it could be. I only see function names, and I can guess what is happening, but I dont see the node name on which the function is invoked. To see that, I would need to run the scene under debugging 3dsmax build which is available only to ADN members (such as us, but not regular users)... so if you can upload any scene that causes this crash, please go on (simplified or not... we have a 64GB machine ;))

[pokoy]

I owe you one. It seems the crash is not even related to Corona and the lights were coincidentally close to the objects causing the crash... This is a 1:100000 chance so without your questions I would've not been able to find it.

The crash is caused by two referenced objects with a more complicated (but not unusual) modifier stack. I am attaching the file, have a look. The funny thing is they weren't even visible in the render but somehow caused Max to get instable.

Fun stuff to try (Corona and Scanline will both have different issues and both will cause Max to crash at some point):

- hide 'geometry' from being displayed or hide both objects (so no geometry is being rendered) and render
- hide 'Object A' and render
- hide 'Object B' and render
- render both

Depending on the action it renders fine, hangs, gets instable or crashes immediately.
Reporting this to Autodesk now, looks like a severe 3dsmax problem to me.

[pokoy]

FYI, this scene also reports 'Bounding Box too large', might be of help at tracking it down.

[Ondra]

yep, 3dsmax bug. Immediately crashes in scanline + debug 3dsmax build. Nothing we can do, unfortunately.

[pokoy]

I reported it to ADSK when it became clear that it's a bug in Max, they also have the scene. Fingers crossed.