I'm having the exact same problem. 2 days ago everything worked fine, yesterday tried to render something and it started to give me error: something went wrong. I then uninstalled blender, reinstalled it and it doesn't matter if I use the install addon button or install it manually, the button is just not clickable.
Same thing happened on my laptop with 2.57+ corresponding script and 2.58. 2.56+ its addon works fine...
First picture shows what happens if I use 2.57+ octanerender.v1.09b and try to render something.
Its weird that I have no idea what I've done wrong, the scripts have always worked for me with 2.56,2.57,2.58, but now
E: okay, I got it working so I can enable the addon(had to delete the octane plugin folder from Roaming), but whenever I try to render something this happens(1st image):
E2: Everything's working now. Problem was caused by appending objects from another blend file