MacOs X on iMac Prorender 2.2.1 Blender 18.104.22.168
Thank you for request. That's RPR issues reproduce with Windows and Ubuntu systems. Will be fixed in future builds.
I have found that I will get that same error if I try to render any material which uses a "curve" node, such as RGB Curve or Vector Curve Nodes. I don't believe these curve nodes are supported by ProRender yet. So if you are using that node anywhere in your problem scene, I would try removing it to see if the error goes away.
Thank you for request. that's node was changed by Blender side and 2.82 is a beta version for now. The current issue will be fixed before Blender 2.82 release
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