I erased an APFS Volume containing a second OSX installation (trying out Mojave) but the Mac keeps trying to boot into it

apfsbootdisk-utilitydisk-volumemojave

I added a Second Volume to my Main APFS Container to install and try Mojave (I'm running High Sierra). I decided that Mojave is not for me and I erased the volume from Disk Utility. My Mac still tries to boot into Mojave by default when I restart my computer (it fails because that volume doesn't exist anymore).

In order to go into my High Sierra OS, I always have to boot with Alt pressed to choose the boot disk. If I don't do this, I get the "?" icon.

The weird thing is that this volume was indeed erased and does not appear on Disk Utility nor on the Startup Disk menu in System Preferences.

How can I fix this? I want to remove the "Mojave" Volume from the boot disks so that my computer will start normally when I turn it on.

EDIT: I seem to have found something useful in this post, but it is for people who still haven't erased the volume from Disk Utility. I don't know how to do it in my case, where I already erased it.

Best Answer

You can change the default to boot High Sierra by either of the following:

Select High Sierra from the Startup Disk pain of the System Preferences application.
Hold down the control key when selecting High Sierra from the Startup Manager.

You still have Mojave code in your APFS container. In your case, do the opposite of the answer you linked to.

BTW: You can also elect to not delete this code. The code will not interfere with the operation of the Mac and occupies very little space.

IN OTHER WORDS:

Note: Below I have assumed APFS Volume "Preboot" is disk2s2 and APFS Volume "My Recovery" is disk2s3.

You can use Disk Utility under High Sierra to remove the APFS volume containing Mojave. However, removing Mojave also requires steps where commands are issued in a Terminal application window. Below are the remain steps needed to remove Mojave.

Open the Disk Utility application.
Get the file system UUID of the High Sierra volume . Right click the icon for the High Sierra volume in the Disk Utility application and select Get Info. Here, I will assume the file system UUID is 2E0E6320-5D0A-4181-B465-ABFF2CBBFC27.
Boot to macOS Recovery.
Open a Terminal application window.
Enter the command below to disable System Integrity Protect (SIP) on next restart.
```
sudo  csrutil  disable
```
Boot back to High Sierra.
Open a Terminal application Window.
Determine the UUID of the deleted APFS Mojave volume. Start by entering the commands given below.
```
diskutil  mount  disk2s2
cd  /Volumes/Preboot
ls
```
The UUID of the deleted APFS Mojave volume should be the same as the name of the directory (folder) that is not the UUID for the High Sierra volume (2E0E6320-5D0A-4181-B465-ABFF2CBBFC27). Here, I will assume this is 832D1AE3-C9F2-454F-BE45-64E1ECBA38AA.

Enter the commands below to remove Mojave from APFS Volume Preboot.

rm  -Rf  832D1AE3-C9F2-454F-BE45-64E1ECBA38AA
cd  ~
diskutil  unmount  disk2s2

Enter the commands below to remove Mojave from APFS Volume My Recovery.

diskutil  mount  disk2s3
cd  "/Volumes/My Recovery"
rm  -Rf  832D1AE3-C9F2-454F-BE45-64E1ECBA38AA
cd  ~
diskutil  unmount  disk2s3

Reset the SIP settings, by entering the command given below.
```
sudo  csrutil  clear
```
Restart the Mac

Related Solutions

MacOS – APFS – Is it possible to install 2 macOS versions inside one APFS container

Yes, it possible to have multiple macOS installations inside a single container with multiple virtual partitions, but some of the partitions will be shared.

Note: I do not think virtual partitions is the correct terminology. I believe the terminology should be APFS volumes sharing the same APFS partition.

I started with High Sierra installed to volume labeled Macintosh HD in a APFS container. I using the Disk Utility application to add a new APFS volume labeled Macintosh HD 2. Next, I downloaded High Sierra from the App Store and installed to the Macintosh HD 2 volume. The result from diskutil list is shown below.

Note: I used a external drive, so disk2 appears below instead of the expected disk1.

/dev/disk2 (synthesized):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      APFS Container Scheme -                      +200.0 GB   disk2
                                 Physical Store disk1s6
   1:                APFS Volume Macintosh HD            50.8 GB    disk2s1
   2:                APFS Volume Preboot                 46.1 MB    disk2s2
   3:                APFS Volume My Recovery             1.0 GB     disk2s3
   4:                APFS Volume VM                      8.6 GB     disk2s4
   5:                APFS Volume Machintosh HD 2         18.2 GB    disk2s5

While both High Sierra installations use different root volumes (disk2s1 and disk2s5), the installations share disk2s2, disk2s3 and disk2s4.

Next, I created another APFS volume labeled Mojava 1 and then downloaded Mojava Beta from this Apple website. The result after installing is shown below.

/dev/disk2 (synthesized):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      APFS Container Scheme -                      +200.0 GB   disk2
                                 Physical Store disk1s6
   1:                APFS Volume Macintosh HD            50.8 GB    disk2s1
   2:                APFS Volume Preboot                 74.5 MB    disk2s2
   3:                APFS Volume My Recovery             1.5 GB     disk2s3
   4:                APFS Volume VM                      8.6 GB     disk2s4
   5:                APFS Volume Machintosh HD 2         18.1 GB    disk2s5
   6:                APFS Volume Mojava 1                35.8 GB    disk2s6

Mojava installed to disk2s6 and shares share disk2s2, disk2s3 and disk2s4 with the other two High Sierra installations.

So there is now three macOS Recoveries for both High Sierra and Mojava. In my case, both High Sierra macOS Recoveries are Version 1.0 (327) and the Mojava macOS Recovery is Version 1.0 (330).

I can boot to one of the three macOS Recoveries stored on disk2s3 by holding down the ⌘+R key combination at startup. If the default startup disk is a APFS volume containing macOS, then the corresponding macOS recovery will startup. For example, if the startup disk is set to the APFS volume Machintosh HD 2, then holding down the ⌘+R key combination at startup will result in the Mac booting to High Sierra macOS Recovery on APFS Volume My Recovery.

Note: macOS Recovery no longer appears in the Mac Startup Manager. However, macOS Recovery, for a given macOS installation, can be booted using the rEFInd Boot Manager.

BTW: Removing Mojave from the APFS container is covering in my answer to the question: Erase an APFS volume?

Remove macOS from a APFS container

This answer is a continuation of my answer to the question: APFS - Is it possible to install 2 macOS versions inside one APFS container?

You can use Disk Utility under High Sierra to remove the APFS volume containing Mojava. However, removing Mojave also requires steps where commands are issued in a Terminal application window. Below are the steps I used to remove the Mojava.

Open the Disk Utility application.
Get the file system UUID of the Mojave 1 volume . Right click the icon labeled Mojava 1 in the Disk Utility application and select Get Info. In my case, the file system UUID is 0FF6C520-6C07-40ED-9AED-FD6E28A6E406.
Use Disk Utility to remove the APFS volume containing Mojava. Right click on the icon labeled Mojava 1 in the Disk Utility application and select Delete APFS Volume....
Boot to macOS Recovery.
Open a Terminal application window.
Enter the command below to disable System Integrity Protect (SIP) on next restart.
```
sudo  csrutil  disable
```
Boot back to High Sierra.
Open a Terminal application Window.

Enter the commands below to remove Mojava from APFS Volume Preboot.

diskutil  mount  disk2s2
cd /Volumes/Preboot
rm  -Rf  0FF6C520-6C07-40ED-9AED-FD6E28A6E406
cd  ~
diskutil  unmount  disk2s2

Enter the commands below to remove Mojava from APFS Volume My Recovery.

diskutil  mount  disk2s3
cd  "/Volumes/My Recovery"
rm  -Rf  0FF6C520-6C07-40ED-9AED-FD6E28A6E406
cd  ~
diskutil  unmount  disk2s3

Reset the SIP settings, by entering the command given below.
```
sudo  csrutil  clear
```
Restart the Mac

Best Answer

Related Solutions

MacOS – APFS – Is it possible to install 2 macOS versions inside one APFS container

Remove macOS from a APFS container

Related Question