'Incompatible Format' for partition in disk utility
I have two partitions on my early 2011 MacBook Pro, one is 10.6.8 which I use for my old version of Logic Pro and the other is a Mavericks partition that I've been trying to install Yosemite on.
I've been having all sorts of problems with Yosemite but my 10.6.8 partition works fine. Previously I could access files from across partitions and see the other partition fine but I no longer can. Under disk utility it says that my Yosemite partition is an 'Incompatible Format' now and I can't access it at all.
Everything important on there I have backed up but would like to be able to check through the partition for any files I've missed before I seemingly have to just do a restore on it.
Any ideas on how I can do this would be much appreciated!
MacBook Pro (15-inch Early 2011), OS X Yosemite (10.10)