Sorry, I missed that you want to use Blender 4.0.
The last compatible addon version with Blender 4.0 is 1.0.7.
I have just tried to copy a groom from 4.1 to 4.0. The connections are instantly broken. Blender 4.1 had some important updates in Geometry Nodes department.
But If you just want to use the groom in the 4.0, you can apply the Geometry Nodes modifier on the Hair object and copy-paste it into the 4.0.
Great thanks. Iāll try that on the scene I posted above and Iāll reinstall the 1.0.7 version for the new Octane scene Iām working on. Thanks for all your help. 
Just like any other object, one can append or link Medusa Nodes groom objects into different scene (for rendering or staging purpose).
In the end itās a regular hair curves object with custom Geometry Nodes modifier.
I havenāt tested the overrides with Medusa Nodes hair objects yet. As far as I know not every data-block can be overridden, but maybe I am wrong on that.
You are welcome, @Musashidan 
I copied all the collapsed geo nodes across to 4.0 Octane. I also found a very handy Octane setting thatās available on these collapsed hair curves
You are correct, not everything can be overridden, but if linking and all that works then thatās the main thing at this stage.
Do you get that error in the new and clean 4.0 scene or are there any Medusa Nodesā groom objects in it? Because the new nodes from 1.1.3 will not work with the older addon version.
No, this is the error I get on a completely clean scene. Iām not trying to append or copy/paste any grooms from other scenes, Iām just trying to add new ones into a fresh scene. As soon as I add a groom object I get this error.
Ok, that is not a good sign if after starting a new groom you get this error.
I have just tested it again on Blender version 4.0.2 and the addon version 1.0.7
No issues on my end.
Could you maybe manually remove and re-install the version 1.0.7?
Thanks. Itās not a huge deal as I know you shouldnāt have to worry about old versions. The issue could be within the special Octane build itself? Iāll just stick to Cycles for the moment, but the quality of skin especially just isnāt on the level of a renderer like Octane or Arnold.
Ok, I hope cycles will play along nicely and you will achieve the desired look:)
Some exposure for Medusa. Front page of Blender Nation. 
I gave Medusa a glowing review in that post too.
Oh, that is amazing! I am happy to see your post there. Thank you for the kind review as well, it is truly motivating.
spamming this thread with a render. Medusa nodes used on eyebrows and eyelashes! hopefully for my next project I will work on someone with a full head of hair, where I can play more with Medusa
if you wanna see more content on this model, here is the thread ( sorry for the spam )
Nice one, Alex, thanks for sharing your art here!
Great news, one downside; now I canāt wait to see it.
Thereās a feature in the Houdini grooming tools that let you set guide influence radius. So if you set the global hair creation from guides to off and start placing guides manually, hairs will only appear around the guide, based on the influence setting.
This is one thing I donāt like about Medusa, when you place the first guide hair appears everywhere. It makes it visually difficult to groom. Or maybe there is a way to do this in Medusa that I donāt know about?
Do you mean something like the function shown in the clip in my previous answer to metamesh?
It will be in the next update.
4.2 support would be nice!
4.2 is supported.
