Q: Win 10 installer on MBP2011 produces "couldn't create new partition" error
I'm trying to install Windows 10 on my late 2011 Macbook Pro. As it's not officially supported, I'm bypassing the use of boot camp assistant.
I have a 256GB SSD hosting OSX, I'd like to split that for Windows.
As I've read elsewhere, I created a FAT32 partition with diskutil command, set boot flags (as described here http://tinyurl.com/jrt9e2y), and fixed up GPT boot records (as described here http://tinyurl.com/l5q4tkt).
When I boot up on a Win10 installer usb drive, I select the partition, hit "format" to convert it to NTFS, and I get the error below. What can be done? Seemingly the installer creates its additional partitions, so I don't know why the error happens.

MacBook Pro, OS X El Capitan (10.11.2), null
Posted on Dec 29, 2015 4:44 AM
In addition to what BobTheFisherman correctly writes, also make absolutely certain you have complete backups of all of your partitions.
You will want to generate those backups first, and then use the Apple Boot Camp procedures or use the procedures specific to whichever virtual machine you might have installed. Or have a chat with the folks behind the directions you're following. As was mentioned.
Why backups? Any partitioning-related failures here that might arise with any of the partitioning tools can potentially lead to disk corruptions and data loss. Partitioning should be treated with great caution — when it goes wrong, corruptions and data loss can result.
FWIW, OS X boot disks are almost always GPT-formatted.
AFAIK, Microsoft Windows doesn't normally get installed on FAT32 volumes, and hasn't in many years.
Posted on Dec 29, 2015 10:33 AM