Unhandled exception when rendering via backburner

[ben_hamburg]

Hey there,

are there any known issues that only come up when rendering via backburner?

From time to time i get errors in the farm with "unhandled exception". In this current case it is "Preparing instances. last marker is at ./src/Vrayrenderer.cpp,line426: Preparing camera sampler".

I just don´t get why I only get this problem when rendering in the farm, but not locally on either of the two workstation with Vray workstation licenses...
Its an older scene, but nothing particularily fancy, no cached files used.
Just wondering if you have an idea where to start troubleshooting this, since I probably won´t have time and I´ll just render it over night...

[3d-laboratory]

Dont know if it has to do something with it. When I render via backburner and have the "VRay-->Frame Bufffer-->Enable built-in frame buffer activated and netrender activated it sometimes comes to crashes when i try to open another scene. As you probably know you have to deactivate the VFB if you want too render different render elements via backburner. In the beginning with VRay I also had problems with backburner, but it runs very stable since months. (VRay 3.60.04 with Max2018.

[ben_hamburg]

Well, if I have some time I´ll try disabling Pflow first, I had issues with that before I think.

[Martin.Minev]

Can you try, whether the issue occurs when you run Backburner locally. Do you have any other plugins used in that scene, which are missing on the farm? If the issue still persists, please send us the scene along with assets to support@chaosgroup.com for investigation.

[ben_hamburg]

hey, there shouldn´t be any plugins-issues, we use the same plugins over and over (phoenix, forest pack) and they are all in the farm as well...unfortunately I cranked out so many shots lately, I completely forgot which shot was giving me issues...But I can most likely pretty easily recreate that problem with motion blur and particles, so I´ll try to get a scene together asap...

[ben_hamburg]

Ok, so I stumbled into that issue again and its not just in backburner.
It happens with particle flow and motion blur enabled. I had some time to test this further and I pinned the problem down to copied particle flows.
So the setup was: I had the camera move a long a certain distance I had to cover with a lot of particles, and I would have had to emit millions of particles to cover the whole area. So instead I used several emitter objects along the path and copied the particle flow, only changing out the emitter objects.
The first Pflow rendered fine with motion blur, but the consecutive ones all gave me the "unhandled exception" error.
There was a problem, I think since Max 2018, that made pflows from previous versions not work anymore. It got fixed somewhere in 2019, but the workaround at the time was to just delete the pflow source event, create an empty pflow and connect that to the copied pflow.
So I did that and alas, the problem is gone, now the copied pflows also render.

This is probably a 3ds Max issue and not a Vray one, but I´m still leaving this here in case it isn´t or for anyone else having the same issue...