I'm pretty sure you are going to have to format it to get the new OS on the HDD. You can either use a cloud to backup the data you don't want to lose or buy another hard drive and back it up on that.
I'm pretty sure you are going to have to format it to get the new OS on the HDD. You can either use a cloud to backup the data you don't want to lose or buy another hard drive and back it up on that.