I'm assuming you are using the blender exporter in some version of windows?
I had the same problem, first problem was having spaces in the path to the "project path", which I fixed (by removing that spaces in the path).
Then I got the error telling me I had spaces in the "octane binary path", which is referring the path to "octane.exe", which in windows, is installed to C:\Program Files\blah\blah...
By default there is a space in "Program Files", and in some of the other subfolders that are created when you install Octane, so I reinstalled Octane to a specific folder with no spaces, e.g. "X:\RefractiveSoftware\Octane\" and then the script started to work for me.
I'm not sure where this limitation comes from, haven't done enough research, but it would be nice that if this is going to be a permanent issue (spaces not being allowed in pathnames), that when Octane installs, it either reminds you about this issue or else automatically installs itself in a path with no spaces...which would be hard since "Program Files" has a space in it to start with.
Win 7 64bit | GeForce 8800 GTS | AMD Athlon 64 FX-62 | 4GB
OSX 10.6.5 | Quadro 4800 | 2 x 2.93 GHz Quad-Core Intel Xeon | 16 GB