MacOS Sierra installation not possible (no start volume)

Question

Level 1

8 points

MacOS Sierra installation not possible (no start volume)

Hello everyone

I have an iMac with the following specifications:

and I'm trying to install the new MacOS Sierra. But every time I open the installer, It tells me that I cannot use the partition called "Mac OS X", which is my main Mac partition on my fusion drive, for the install of Sierra since it cannot be used as a start volume. This of course is complete nonsense since I am starting to the "Mac OS X" volume every time I start my Mac!!

This screenshot shows the installer and the associated message:

Could anyone help me please? I really don't want to do an all clean installation and than spend hours restoring all my old settings! Please...?

Best regards

Martin

iMac (27-inch, Late 2012), OS X El Capitan (10.11.6)

Posted on Oct 5, 2016 3:03 PM

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Answer 1

Teddy_B

Community Specialist

Oct 6, 2016 12:19 PM in response to mpauli

Hi mpauli,

I see that the macOS Sierra installer is giving you a message stating "This disk cannot be used to start up your computer." In order to get this issue resolved I suggest that you follow through the troubleshooting steps in the link below.

Installer reports "OS X could not be installed on your computer" or "This disk cannot be used to start up your computer"

Cheers.

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Answer 2

mpauli Author

Level 1

8 points

Oct 10, 2016 8:56 AM in response to Teddy_B

Hi jameson.h

Thanks for the reference to the support article. I should have mentioned that I've already tried this and it didn't work!

The interesting thing is that the Mac OS partition is actually two parts (I always thought it had something to do with the fusion drive). See the image below:

As you can see, there are three partitions, the 500GB Windows partition (small section in the middle) and the two 2.6 TB Mac partitions which in finder only show up as one. I've tried to change the size on each one of them as well as changing the size of both of them. But whatever I do, MacOS Sierra refuses to install in the MacOS drive(s).

Any other help would be highly appreciated. This is the first time I'm stuck on a Mac problem in seven years!!

Best regards

Martin

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Answer 3

rose_10

Community Specialist

Oct 11, 2016 12:51 PM in response to mpauli

Hi Martin,

Thanks for the additional details. If you were unable to get it to be installed after resizing the partition, then you will need to back up your drive and reformat the disk.

Use Time Machine to back up or restore your Mac

How to reinstall macOS

Take care.

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Answer 4

Oct 19, 2016 2:24 PM in response to rose_10

I'm experiencing the same issue... however, formatting my drive doesn't really suit me as a solution, I've done so many upgrades even to Beta versions of MacOS and never had an issue, don't think should be any different with macOS Sierra.

Anyone can please help us.

Cheers.

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