Can't boot back into OS X from Windows 10

Question

Can't boot back into OS X from Windows 10

Hey all, I'm sure everyone that's downloaded and upgraded their Windows 7/8(.1) partition has encountered dramatic problems over the last couple of days. Well, so have I, here's my issue on my 27 inch iMac Late 2011 (Yosemite):

After a rather successful installation of Windows 10 32bit, up from 7 (SP1), I've tried booting back into OS X using the Option key upon boot. But, it seems the computer ignores the command and just goes straight into Windows 10. I've tried multiple times and I'm at a loss at what to do. This is extremely frustrating that I cannot get back to where I do all of my work. I've also tried the PRAM reset command, and the Start in recovery command.

When I am in Windows 10, however, it seems only the graphics driver is working. Sound is virtually inaudible (ie, there is sound, but extremely soft, even at 100% volume), and it took a while to get the bluetooth keyboard working.

I have looked through my windows.old folder to try and run the previous BootCamp.exe that Windows 7 used, but alas, it does not even start. So I've redownloaded the Windows 8.1 Boot Camp (version 5.1.5640) drivers, and when I try to run the setup, I get the error message "This app can't run on your PC."

On another note, I cannot see my OS X hard drive partition in the "This PC" window. I know it's still there because the Windows 10 partition is only 326GB in total size, whereas the entire hard drive is around 1TB.

Perhaps the drivers for Windows 10 are not yet available...

Is there anything that I can do? I am losing my mind at the absolute mistake I made this weekend upgrading something that was never broken in the first place.

Yours in desperation,

Will

iMac, OS X Yosemite (10.10), Windows 10

Posted on Aug 2, 2015 10:47 AM

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Answer 1

Loner T

Level 9

59,471 points

Aug 2, 2015 11:02 AM in response to William Roberths

There is no Late 2011 27-in iMac, but there is a Mid-2011 27-in iMac according to How to identify iMac models - Apple Support.

From System requirements to install Windows on your Mac using Boot Camp - Apple Support,

iMac

Mac model	Windows 8 64-bit	Windows 7 64-bit	Windows 7 32-bit	Windows Vista 64-bit	Windows Vista 32-bit	Windows XP 32-bit
iMac (27-inch, Mid 2011)	5	5	4	-	-	-

The drivers for W7 64-bit are Boot Camp Support Software 5.1.5621 not 5.1.5640.

Post Date: Feb 11, 2014

File Size: 924.9 MB

System Requirements

MacBook Air (11-inch & 13-inch, Mid 2011)
MacBook Air (11-inch & 13-inch, Mid 2012)
MacBook Pro (15-inch & 17-inch, Mid 2010)
MacBook Pro (13-inch, & 15-inch, Early 2011)
MacBook Pro (17-inch, Early 2011)
MacBook Pro (13-inch,15-inch & 17-inch Late 2011)
MacBook Pro (13-inch & 15-inch, Mid 2012)
MacBook Pro (Retina, Mid 2012)
MacBook Pro (Retina, 13-inch, Late 2012)
MacBook Pro (Retina, 13-inch and 15-inch, Early 2013)
Mac Pro (Early 2009)
Mac Pro (Mid 2010)
Mac Pro (Mid 2012)
Mac mini (Mid 2011)
Mac mini (Late 2012)
iMac (27-inch, Mid 2010)
iMac (21.5-inch & 27-inch, Mid 2011)
iMac (21.5-inch & 27-inch, Late 2012)
iMac (21.5-inch) Early 2013
Windows 7, Windows 8, and Windows 8.1, 64 bit

You may want to try re-downloading .5621 to a USB2 flash drive, and install it using Boot Camp: Install or repair Boot Camp drivers or Boot Camp: Solve Windows support software installation problems . The latter link addresses devices, but the first link will repair all drivers and non-driver binaries. This must be done using Run as Administrator and W7 compatibility mode. This may or may not work, though.

W10 has no officially supported drivers yet. 😉 . Bleeding edge causes severe bleeding.

Yosemite may use a CoreStorage volume rather than a simple JHFS+ volume/filesystem. There are no Windows drivers to allow readability of such volumes. One option to use is a diskutil cs revert command on the OS X side, if permitted, and the gain visibility of the OS X volume from Windows.

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Answer 2

Aug 3, 2015 2:24 PM in response to Loner T

Hey Loner T,

I've done as you instructed, but I am still faced with the error message: "This app can't run on your PC."

I am at an absolute loss at what to do right now 😟 I feel as if Windows has invaded and destroyed my Mac.

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Answer 3

Loner T

Level 9

59,471 points

Aug 3, 2015 2:32 PM in response to William Roberths

Are you running setup.exe from the Bootcamp folder?

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Answer 4

Aug 4, 2015 5:29 AM in response to Loner T

Yes, I am.

However, I'm going to reinstall windows 10 as a 64bit architecture instead of 32. Because the boot camp support software for my specific iMac is 64b, it would only make sense to do a reinstall and then run the software from there.

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