OS X Base System only disk available

Hi! I had problems with my iMac and tried to erase the OS and re-install, but I did something wrong and now all I have is asingle partition with OS X Base System that is the size of my HD (1 TB), see picture 1. This new disk image cannot be partitioned: when I hit the + sign in the partition screen, nothing happens. In the Disk Utility, the options for erase, restore and unmount are all unavailable (see picture 2), I imagine that's because you normally cannot do any of these on the OS X Base System disk. This disk is also locked, so I cannot re-install High Sierra (see picture 3).

As the OS X Base System is the only thing left in the computer, every time I start it up, it does directly into the Recovery menu.

I've researched on the internet and a lot of people made this mistake. Most of them where able to either erase or re-install the system, but I'm at a dead end, as I don't have any of these options available. I don't know what else to try. Does anyone know how to fix this? Thanks!

Pic 1 - OS X Base System is the only disk available

Pic 2 - When I press the + sign nothing happens

Pic 3 - Cannot reinstall High Sierra as the only disk available is OS X Base System, that is locked

iMac, macOS High Sierra (10.13.3), null

Posted on Feb 9, 2018 9:13 AM

Top-ranking reply

Elements50

Level 1

13 points

Posted on May 2, 2018 12:25 AM

Genius!!!! After searching for help, the Mac finally worked with your step by step instructions!!!! Thank you sooooooo much!!!

To those stuck at the reboot and unable to install, the most important step was the comm-option-r and hold it. Had been doing comm-r and was stuck in the failed heart/brain-painful/frustrating loop.

Follow the step by step given earlier by kappy.. the Mac will reinstall.. which will like another 30 minutes.

Thank you again. It works!!!

Critical step::::;

1. To install the version of OS X that was currently installed use Command-Option-R

2. To install the original factory version when the computer was new use Command-Option-Shift-R

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32 replies

Mar 29, 2018 6:14 AM in response to marcia.marchiori

I have the SAME problem! I followed all steps but it didn't work. When i hold down Command+r the globe doesn't came out ! Comes out the classic loading with Apple and opens the recovery mode

Feb 9, 2018 2:24 PM in response to Csound1

I can change the size in the dialog, but the "Apply" button doesn't come active. I can also change the name of the partition (I tried to change it to "Macintosh HD", for example). When I do it, the "Apply" button becomes active, but when I click it, it returns an error message saying that changes cannot be applied.

Kappy

Level 10

362,007 points

Feb 10, 2018 12:49 PM in response to Csound1

You jumped in with your replies to the OP and stepping over an already ongoing discussion. I answered replies I saw directed towards me. However, at the end, I sent out a reply that I see went to you instead of the OP. I reckon I clicked the wrong "Reply" button. Honestly, I didn't pay any attention to what you were posting.

Feb 12, 2018 8:01 PM in response to Csound1

OMG, thank you guys, it worked! So here was the problem: I was going to the "regular" recovery screen, instead of the Internet Recovery one. I was pressing the right buttons, but not for long enough (I would just press it and release real quick). Thanks!

Csound1

Level 9

60,063 points

Feb 9, 2018 2:08 PM in response to marcia.marchiori

In picture 2 it looks as if the size dialog is active, is it? and I yes can you alter it at all?

And, how did you boot the machine, standard, recovery or internet recovery?

Csound1

Level 9

60,063 points

Feb 9, 2018 2:29 PM in response to marcia.marchiori

I am out of ideas I'm afraid, maybe Kappy will fill us in.

Csound1

Level 9

60,063 points

Feb 9, 2018 2:30 PM in response to Csound1

I would still like to know what you are booted to though.

Feb 9, 2018 2:43 PM in response to Csound1

Sorry, forgot to answer that one: I simply turn the computer on and it goes directly to Internet Recovery (without entering any shortcuts during start up).

Csound1

Level 9

60,063 points

Feb 10, 2018 12:52 PM in response to Kappy

nihil cogitant ex eo

Kappy

Level 10

362,007 points

Feb 10, 2018 1:20 PM in response to Csound1

ex nihilo nihil

Csound1

Level 9

60,063 points

Feb 10, 2018 1:21 PM in response to Kappy

Such a deal.

Kappy

Level 10

362,007 points

Feb 10, 2018 1:28 PM in response to Csound1

For a nickel, shouldn't be a total loss. (said with a NY Jewish accent.)

Csound1

Level 9

60,063 points

Feb 10, 2018 1:31 PM in response to Kappy

What's a nickel?

Kappy

Level 10

362,007 points

Feb 10, 2018 2:16 PM in response to Csound1

Five cents.

Csound1

Level 9

60,063 points

Feb 10, 2018 2:20 PM in response to Kappy

There is a thing for such a trifle 😕

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OS X Base System only disk available