MacOS – Getting Errors. I need help downgrading to Mountain Lion from High Sierra through internet recovery

apfsdowngradehigh sierramacos

I can't find a disk to select to install OS X in Internet Recovery Mode. Also I can not erase the disk or partition. I gave all the details.

Two days ago I decided to do a clean wipe on my MacBook Pro with factory SSD and Mountain Lion. I not able to reinstall the fresh OS X Mountain Lion from Internet recovery because the drive to select wont show up when you have to pick where to install the OS X in Disk Utility. If I try to erase the original disk start up it just hangs and says it's partitioning. I gave a detailed description from start to now on what is happening can anyone help? I believe it has to be fixed some how in terminal.

First I went into my local recovery of High Sierra and did an erase of the disk.

Then I did an Internet Recovery and erased the disk0s2 partition. (Everything went good)
After that I did an erase for the main disk start up 500.28 GB Apple SSD SD512E Media. (Which got stuck or my internet crashed) I quit disk utility.

Then I got back in Internet Recovery and again I tried to erase the disk start up 500.28 GB Apple SSD SD512E Media. (This time on the bottom right corner where it shows a progress bar it starts out with and stays in Partitioning. Estimated time less than 1 minute but it never progresses and the time keeps growing I tried leaving it for over 12 hours and a few other attempts no luck).

I checked my system with the quick AHT and everything is fine got no issues. Did the test a few times.

I think I will have to do something in terminal. I believe the drives are getting confused with some sort of formatting issues. Below I have stated what exactly happens and all the options I have available in Disk Utility.

When I restart and go into internet recovery mode. disk0s2 partition always comes back but is grayed out. If I click on it all buttons are grayed out as well cant do anything other than erase. When I erase it I get this error: Volume Erase Failed. Volume Erase failed with error: MediaKit reports bad partition or no map found.

After trying to Erase disk0s2 partition if I try to erase the main disk start up 500.28 GB Apple SSD SD512E Media I always get the same issue where in the right bottom corner it shows the progress that it is Partitioning. Estimated time less….and the time keeps climbing slowly till it hangs.

Now after if I have attempted to erase the main disk 500.28 GB Apple SSD SD512E Media. Things change than they are at first from without having any erase attempts. After the attempts the fix buttons get grayed out with the 500.28 GB Apple SSD SD512E Media. Before any erase attempts on partition tab on main disk I am able to verify disk it says everything is good and partition is ok. When I try to click repair disk it says Error: Couldn't repair the partition map…EFI system partition could not be created. I can open the partition tab and see disk0s2 but everything is grayed out but keeping in mind if I try to erase the disk0s2 or 500.28 GB Apple SSD SD512E Media the partition tab becomes empty where I can created another partition but it never happens and gets stuck in the progress bar in the right corner says waiting for partition to reappear.

This is what 500.28 GB Apple SSD SD512E Media bottom before I try to erase. Do remember that under this disk its the partition disk0s2 which is grayed out but if I try to erase it disappears unless I restart and get back into Internet Recovery.

Disk Description : APPLE SSD SD512E Media Total Capacity : 500.28 GB (500,277,790,720 Bytes)
Connection Bus : SATA Write Status : Read/Write
Type and Location : Solid State Disk, Internal S.M.A.R.T. Status : Verified
Partition Map Scheme : GUID Partition Table

500.28 GB Apple SSD SD512E Media bottom after I try to erase. You can see how the Partition Map Scheme chages but this is after I try to erase and cancle where it gets stuck in Partitioning. Estimated….time.

All I need is help on how to get a disk to pick out to put Mountain Lion on. Right now it shows nothing and the install button is grayed out. Does it have something to with the sizes of the partitions not matching up to the total amount I have available?

This is what diskutil list looks like. I am not very tech-savvy but this is all the information I can offer. I don't understand why I have so many partitions when in Disk Utility all I see is 500.28 GB Apple SSD SD512E Media and under it disk0s2 which is grayed out.

-bash-3.2# diskutil list

/dev/disk0
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *500.3 GB   disk0
   1:                        EFI                         209.7 MB   disk0s1
   2: 7C3457EF-0000-11AA-AA11-00306543ECAC               500.1 GB   disk0s2

/dev/disk1
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:     Apple_partition_scheme                        *1.2 GB     disk1
   1:        Apple_partition_map                         30.7 KB    disk1s1
   2:                  Apple_HFS Mac OS X Base System    1.2 GB     disk1s2

/dev/disk2
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               *524.3 KB   disk2

/dev/disk3
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               *524.3 KB   disk3

/dev/disk4
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               *524.3 KB   disk4

/dev/disk5
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               *524.3 KB   disk5

/dev/disk6
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               *524.3 KB   disk6

/dev/disk7
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               *6.3 MB     disk7

/dev/disk8
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               *2.1 MB     disk8

/dev/disk9
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               *1.0 MB     disk9

/dev/disk10
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               *524.3 KB   disk10

/dev/disk11
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               *524.3 KB   disk11

/dev/disk12
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                            untitled               *1.0 MB     disk12

Best Answer

While upgrading to High Sierra the main partition of an SSD (disk0s2) is converted to APFS - Apple's new file system introduced 2016 in Sierra.

Older system versions like Mountain Lion don't contain APFS drivers and neither diskutil nor Disk Utility can handle the partition type of file system properly. In Internet Recover Mode (depends on the key combination) you are probably booted to a Mountain Lion base system.

There are several methods to remove the "unknown" partition.

One is outlined below:

In Internet Recovery Mode open Terminal: menubar > Utilities
Enter diskutil list to get the details

Usually the internal disk has the device node disk0. All other disks are either external disks or related to Internet Recovery Mode (disk1-disk12 in your example)
If external disks are attached (probably all disks larger than 2 GB - including thumb drives, but don't unmount/eject your internal disk), unmount, eject and detach them:
```
diskutil umountDisk diskX
diskutil eject diskX
```
Remove the APFS container partition and EFI:
```
gpt destroy /dev/disk0
```
Create a new partition table:
```
gpt create -f /dev/disk0
exit
```
Exit Terminal and open Disk Utility in the Utilities window
Partition and format the disk as needed
1. In the left pane choose the 500 GB drive at the top
2. Hit the "Partition..." tab in the larger right pane
3. Choose "1 Partition" in the partition layout drop-down menu
4. Choose a name
5. Choose Mac OS Extended (journaled) as format
6. Hit apply

Related Solutions

MacOS – How to install Mountain Lion on a disk that cannot be formatted in recovery mode

You should be able to use dd to destroy the partition's header. You can then format (erase) it and run the install.

From the installer run Terminal and type the following:

dd if=/dev/zero of=/dev/disk0s2 bs=1024 count=1024

Do be warned, this will irrecoverably destroy all data on that partition. But it looks like that's what you're expecting. Make sure you don't accidentally target the wrong thing.

Also note that I haven't done this, exactly. I've used this technique to destroy the entire partition table, not just a single partition. But I think it should work.

When you're done quit Terminal and run Disk Utility. You won't get any complaints about Core Storage.

MacOS – How to extract the Mountain Lion installer from the recovery partition

You don't need to worry about having to copy any data, making USB sticks or having the media present. Use Mountain Lion's Internet Recovery procedure, all files is downloaded and installed on the new drive without having any files.

You replace the HDD and start with Command-R...

See OS X Internet Recovery for more info about the procedure, quote:

If you happen to encounter a situation in which you cannot start from the Recovery System, such as your hard drive stopped responding or you installed a new hard drive without OS X installed, new Mac models introduced after public availability of OS X Lion or OS X Mountain Lion, automatically use the OS X Internet Recovery feature if the Recovery System (Command-R method above) doesn't work. OS X Internet Recovery lets you start your Mac directly from Apple's Servers. The system runs a quick test of your memory and hard drive to ensure there are no hardware issues.

OS X Internet Recovery presents a limited interface at first, with only the ability to select your preferred Wi-Fi network and, if needed, enter the WPA passphrase. Next, OS X Internet Recovery will download and start from a Recovery System image. From there, you are offered all the same utilities and functions described above.

Regarding "Where is the [OS X] disk image hidden?", the Recovery Partition is a minimal bootstrap that connects to a wi-fi network to download the complete OS X 10.8 install, that's why it is so small. See here for further info: About OS X Recovery.

Best Answer

Related Solutions

MacOS – How to install Mountain Lion on a disk that cannot be formatted in recovery mode

MacOS – How to extract the Mountain Lion installer from the recovery partition

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