I have a simple pdg scene where a mesh is uploaded and has a material applied to it (according to a csv file) then a render is processed.
The bug happens at rendertime where the error comes from the ropfetch node, saying that: No output path parameters found on target ROP node
It seems that the render happens but that the file does not write on disk...
I am using Vray for Houdini so maybe the problem comes from there...
What is frustrating is that this problem was solved 3 weeks ago (I don't know why but, it suddenly worked) and today it is happening again.
Any idea what could be the issue ??
Your help would be greatly appreciated!
Thank you!
Alain

This is definetely a Vray bug as it worked after reverting back to Vray 6.2
Thank you.

The ROP Fetch TOP looks for an output file parameter on the target ROP in order to determine where the ROP writes its files. That's necessary for e.g. caching support, so that TOPs can know what outputs already exist before cooking any of the work items.

When the ROP Fetch isn't able to determine which parameter on the ROP defines the output path(s), it issues a warning. It is just a warning though -- not an error -- and TOPs will still cook the ROP. It just can't providing caching functionality or output file reporting since it doesn't know what file paths are going to be produced.

If this used to work before, and doesn't in newer versions, it sounds like the Vray ROP has changed it's parameter interface and renamed the parameter it uses to define output paths. By default, TOPs checks the ROP node for any of the following file parameters: vm_picture, sopoutput, dopoutput, lopoutput, picture, copoutput, filename, usdfile, file, output, outputfilepath, outputimage, outfile#.

You can explicitly tell TOPs which parameter on the ROP node defines the output file path by setting the Output Parm Name on the ROP Fetch TOP, as described in the docs here: https://www.sidefx.com/docs/houdini/nodes/top/ropfetch.html#customoutput [www.sidefx.com]

I don't have Vray installed, so I can't check myself. But double check the name of the output parm on the Vray ROP, and set that as the Output Parm Name on the TOP node.

It is working again. It wasn't a Vray bug after all. I was loading a "rop" attribute in my csv file and that caused the bug. Just renaming "rop" to "my_rop" fixed the issue.