Bootcamp partition not showing up after OS partition resize I have a MacBookPro mid 2012 with OSX El Căpitan and yesterday I resized my OSX partition in order to make more room for the bootcamp partition (Win. 8.1). After I decreased the OSX partition I tried to log into the bootcamp partition but it didn't show up anymore, even if it appears Ok in finder. Would you please help me to recover it ?

Thanks a lot,

Emil
Usually, in order to enlarge your Windows partition, you have to relocate the entire partition. Or, in other words, there usually is not way using OS X to enlarge the Windows partition after shrinking the OS X partition. You can, for example, remove Windows completely and then reinstall Windows to a larger partition. There are also third party tools, such as Winclone, that can be used to backup a Windows partition, shrink the OS X partition, create a larger empty Windows partition, then restore Windows to this larger partition.

I am not sure how just shrinking the OS X partition alone would cause Windows not to boot. One idea is that the type of partitioning was changed. In other words, you either had a pure or hybrid GPT partitioned drive and, after shrinking the OS X partition, the partitioning changed from pure to hybrid or hybrid to pure.

A pure GPT partitioned drive requires Windows to use the EFI to boot, where as a hybrid GPT partitioned drive requires Windows to use the BIOS to boot. So the questions are what is your current partitioning scheme and how does Windows intend to boot?

The following Terminal application commands can be use to determine you current partitioning scheme. None these commands will change your computer.

diskutil list
sudo gpt -r show /dev/disk0
sudo fdisk /dev/disk0


If fdisk shows more than one partition, then Windows will assume to use a BIOS boot method, otherwise the EFI method will be used.

You can determine if Windows was using a EFI boot method by viewing the contents of the hidden EFI partition. To view the contents in the Finder, enter the following command.

diskutil mountvolume /dev/disk0s1

After viewing the contents, you can hide the partition by entering the following command.

diskutil unmountvolume /dev/disk0s1


What you are looking for is a folder labeled Windows. If found, then Windows probably was using the EFI boot method, otherwise the boot method was probably BIOS based.

If the wrong boot method is being used, then the partition tables need to be repaired. The proper steps to repair the tables depends on the contents of the tables. In other words, you will need to first post the output from the first set of commands given in this answer.