Downgrading

tonyberinson

macrumors member
Original poster
Jul 19, 2008
72
35
Hi All,

I am considering downgrading back to Mojave.

Been reading online that people suggest get a book drive etc. etc - and go from there - however with the format of the new drives seems to cause an issue.

Anyone got some instructions on how to do it - successfully.?

Thanks
 

shafez

macrumors member
Jul 3, 2011
93
21
Egypt
Option 1:
- Get a different usb stick than the one which was used to install Catalina.
- Download Install Disk Creator
https://macdaddy.io/install-disk-creator/
- Create Mojave install usb and reboot to the install disk.
- Use disk utility to erase your disk and clean install Mojave.
Option 2:
- Reboot to you Time Machine disk.
- Use disk utility to erase your disk then restore your backup.
Good luck, regards
 

tonyberinson

macrumors member
Original poster
Jul 19, 2008
72
35
Option 1:
- Get a different usb stick than the one which was used to install Catalina.
- Download Install Disk Creator
https://macdaddy.io/install-disk-creator/
- Create Mojave install usb and reboot to the install disk.
- Use disk utility to erase your disk and clean install Mojave.
Option 2:
- Reboot to you Time Machine disk.
- Use disk utility to erase your disk then restore your backup.
Good luck, regards
People have tried this and got an error message. Have you tried this process on Catalina ?
 

shafez

macrumors member
Jul 3, 2011
93
21
Egypt
People have tried this and got an error message. Have you tried this process on Catalina ?
Yes I did, When erasing don't just erase Macintosh HD, Erase the APFS container as Mac OS Extended (Journaled) Or the Apple SSD as Mac OS Extended (Journaled) and it should work.
 

shafez

macrumors member
Jul 3, 2011
93
21
Egypt
Yes I did, When erasing don't just erase Macintosh HD, Erase the APFS container as Mac OS Extended (Journaled) Or the Apple SSD as Mac OS Extended (Journaled) and it should work.
Did it work for you, If yes please mention here so others could get use of it, regards
Sherif
 

faraway52

macrumors member
Mar 3, 2019
30
9
Germany
I have a 2TB external SSD with one container and 3 APFS volumes with active Mojave .
I used one to install the Beta. That worked fine and the portion (let's call it Px) became Px and Px-data.

I wanted to go back with Px to Mojave after some testing of Catalina.

I erased Px and renamed Px-data to Px and restored Mojave with CCC into Px. That worked great and the original Mojave started and ran happy in Px.

The other two APFS partitions Py and Pz in the one and only container on the SSD have not been affected.

However there is something not right as it should be after that procedure. I tried to install Catalina beta in Px again the next day and it failed this time. Download worked fine, the license and copyright passed fine and i dialog popped up "checking "null" or something like that. I assume the downloaded beta file should be checked but the system froze. Retried it twice but was not successfully.

My conclusion is that an existing container with other active APFS systems is not a good test vehicle. There is something left in the container that is not easy visible or removable.
I built the entire SSD new from backups to be on the save side.

My current Catalina beta resides on it's very own external 256GB USB SSD.
 
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