Okay never mind my ranting, I just found a solution for me:
- Login to https://bridge.octanerender.com or https://bridge.octanerender.com/unity
- Unlock all activated licenses for your computer
- Try to activate again
- Done!

Seto wrote:I just reinstalled my computer. Maybe it does matter.

Octane get your shit together and stop letting people do your debugging. It's a stupid licensing system, not even the otherwise good software itself?! Cant believe this...

Same issue with newest Octane and Unity 2018.2.21 for weeks now. I hate online activation systems and your dependency on it soooo damn much!!! Thank god I've got no deadline and are dependent on this otherwise I would hate this even more.

Same problem with 2018.3 and newest Octane. I tried 2 Unity Accounts on two machines and both failed with the same error.

any ETA on this? Have the same problem now, rly distracting just before project deadline ((

That's what I'm wondering as well. For small problems like "The Editor.dll of the Octane plugin is activated for all platforms per default so it's getting in the way of building" a whole forum post seems like too much

will try the Imager, thanks

In other news, I just dragged the Image with the mouse in Octane and it started rendering from scratch, destroying a night of processing

Really GOOD WORK btw finally seeing Octane in Unity. First Test, pretty noisy as I only got a few minutes to render. https://www.dropbox.com/s/q6xvvxk89b0x72s/BadeZimmer.jpg
Any advice how to control the Directional Lights indirect part independently from the intensity as I had to crank it really ...

Or Octane can provide a reduced quality image towards the unity window for preview when a resolution bigger than 4096 is choosen.

Seems it only affects the preview in the Editor, saving a PNG and rendering actually works.