I find that using the texture manager is extremely tedious and there's abnormal long wait time when shifting around the inputs. It used to work fine but now it seems to be completely useless. These are my complaints:

- Octane can't recognize a correct file path if the only difference is a "/" or a ...

If anyone still has this issue I found that you also must disable Multilayer file, then you get out the denoised beauty.

I got the same issue. No matter which pass I remove it's displaying the same message. I tried moving everything to a new document and it's the same thing. Got the newest octane/c4d plugin versions.

UPDATE: the issue was some non-octane materials. After converting them I had no problems.

A. Windows 10
B. 2x 1080 ti 11GB, 1x 1080 8GB
C. 32 GB
D. Nvidia 436.30
E. OctaneRender Standalone v4.04
F. Cinema 4d plugin v4.04.R2
G. Cinema 4d Studio Educational R20

H.
I had my render running for six hours before it crashed. Until then it was very stable. I used the two 1080 ti for rendering ...

I know this comes as a really late answer, but I had the same problem. The solution is to add an Octane Object tag and in the Hair tab select Render as hair. You don't need the hair material on your object, just a regular octane material