ERROR: when batching is enabled

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We are running houdini through tractor for sims and renders and its working quite well however when I submit a wedge by fetching the ropnet containing the wedge I am encountered with this error...

"ERROR: when batching is enabled, the specific ROP must have an output parameter and the preframe and postframe callbacks"

Does anyone have any recommendations on how to deal with this error?
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In order for batch work items to cook properly, they need to be able to set a pre-frame and post-frame script hook on the ROP that's being cooked. This is because PDG needs to know about each frame that finishes for status/output file reporting, and needs to be able to set the active work item for the process before a frame begins so that @attributes evaluate properly. Consequently, batching can only be used if the ROP Fetch node is pointed to a ROP that has pre/post frame script parms on it. This isn't an issue for unbatched frames because each worker process corresponds to a single work item.

If possible, you should point your ROP Fetch to the node inside of the ROP network that you're actually trying to cook. If you need batching because the work item is a simulation, you can also use the "Cook Frames as Single Work Item" toggle. That will cook the full frame range in one Houdini process, but doesn't require the pre/post frame hooks because the entire frame range is cooked as a single work item instead of as a batch. It does mean that all frames of work will be done in that single work item, though, without fine grained progress updates.

I can take a look on our end to see if we can work around the limitation so it can at least cook, but without having access to a post-frame hook the ROP Fetch worker script won't be able to report per-frame progress.
Edited by tpetrick - April 6, 2021 17:39:55
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Thank you for the help clarifying this error.

I am now fetching the wedge node from within the ropnet and ran a successful tractor job.

I did however find that on the ropfetch I needed to be set "evaluate using" to "ROP node Configuration" Other wise it would seem to get stuck in some sort of loop and continuously re-write existing files.... however this working now. We are thrilled to have wedges up and running on the farm.
thank you again!
Edited by Daniel_Lefebre - April 6, 2021 21:59:13
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