How to kill mac - Downgrade Catalina to Mojave

What model mac do you have?

Is it one with the T2 chip?

Yes, mackbook 15'' 2018

okay, have a look at:

https://www.macobserver.com/community/mgg-forum/2018-macbook-pro-trials-travails-and-caveats/

might give you a clue.

Have you figured it out, I have the exact same issue and have an appointment at Apple store until tomorrow.

I have no solution so far. I think I'll have to take the my mac to the service center

I took mine on Sunday to an Apple Store, they were going to attempt using the Apple Configurator to restore it, but if it failed, it would be sent to an Apple repair center. I looked the status online, and it looks like Apple repair center has it and working on it.

Since you do have a machine with a T2, do you have it set (through Recovery) to allow booting from an external disk? I hope I'm not (to you) stating the obvious, but I believe that is off by default.

My 2018 MacBook Pro was bricked by the downgrade attempt. It would not boot at all.

I contacted AppleCare and they are currently repairing it under warranty.

Prior to sending it off, we tried resetting the SMC and restoring the T2 firmware using the Apple Configurator 2 utility (as per the helpful link from luniacdevel)-- neither of which helped. The Configurator got pretty far along, then displayed an error message saying that T2 firmware could not be restored.

Once I get the MBP back, I'll stay on Mojave until Catalina is out of beta for a few weeks. I initialliy installed Catalina in order to try building a macOS version of my iPad app (which fails because several of the third party libraries I use will need to be recompiled first). Meanwhile, Xcode 11 beta runs fine with Mojave on my iMac Pro.

FYI, just got the MBP back from AppleCare. They replaced the logic board and touchID board.

I have exactly the same issue with my macbook pro 13" 2018.

I heard that this "-9000F' error is because Apple only have recovery server for released OS -- and of cause there is no server for Catalina. That means if I patient enough and wait after Catalina release in September, I should able to recover my macbook from brick by Network Recovery?

I have another macbook to finish my daily work so I'm not in a hurry, but just not sure to bring my bricked macbook to repair or just wait...

Same problem here. Cant do anything. should I wait for final release of catalina or what?

I got this error 9000f yesterday and fortunately I was able to fix it by booting into recovery mode using Cmd ⌘ + R and re-installing MacOS Catalina Beta.

What did I do?

I installed MacOS Caltalina on my 2018 MacBook Pro with T2 security chip, used it for about 2 weeks and then decided to go back to Mojave because some of the programs that I use for Web development and photo editing stoppped working correctly.

How I killed my MacBook Pro?

I did not read any downgrade procedure and just booted into recovery and used disk utilities to wipe the SSD. I didn't know that with T2 security chips, you have to enable external drive boot or else you almost brick your laptop.

How I was able to get rid of error 9000f?

• With a freshly wiped SSD and no option to boot using any external drives, I decided to go with internet recovery by pressing Cmd + Shift + R which then asked me to connect to a WiFi, downloaded some stuff with the spinning globe on the screen, then straight away gave me the 9000f error.
• I also tried using Cmd + Option + R to boot into recovery but got the same error again.
• Then I tried using just Cmd ⌘ + R combination while booting up and somehow this time I was able to get to the installation screen that only allowed me to install Catalina Beta (which is okay instead of having a bricked laptop and a possible trip to the Apple store).
• Bottomline, if you're getting error 9000f, the only way ressurect a bricked MacBook Pro with a T2 security chip is to re-install MacOS Catalina Beta.

If you're using the OS on your primary (or only) machine as your daily driver, yes. If you're a beta tester and this is a secondary machine, no. :-)

how to reinstall the macos catalina if i've got a 9000f? where to download the installer

thx

Same happened to me! I was updating macOS Catalina and always got stucked at 26 minutes. Was able to enter internet recovery mode through cmd + option + R (cmd + R gave me 9000F error), download again macOS Catalina beta, and try to reinstall it. Got again stucked at the 26 minutes. Anyone else?

Nope, you're lucky to even have anything different of that 9000F error, I couldn't get rid of it no matter what combination of keys I hold.

The solution is :

1-Another Mac PC with OSX Catalina Beta

2- Or go to https://developer.apple.com/account/ and upgrade to another mac to Catalina Beta

3-From this OSX you can download the .app of catalina Beta

4-Create USB with the command in this web

5-http: //osxdaily.com/2019/06/06/make-macos-catalina-beta-usb-boot-install-drive/

6-Start the PC with option

7-Install from the USB

The solution is :

1-Another Mac PC with OSX Catalina Beta

2- Or go to https://developer.apple.com/account/ and upgrade to another mac to Catalina Beta

3-From this OSX you can download the .app of catalina Beta

4-Create USB with the command in this web

5-http: //osxdaily.com/2019/06/06/make-macos-catalina-beta-usb-boot-install-drive/

6-Start the PC with option

7-Install from the USB

The solution is :

1-Another Mac PC with OSX Catalina Beta

2- Or go to https://developer.apple.com/account/ and upgrade to another mac to Catalina Beta

3-From this OSX you can download the .app of catalina Beta

4-Create USB with the command in this web

5-http: //osxdaily.com/2019/06/06/make-macos-catalina-beta-usb-boot-install-drive/

6-Start the PC with option

7-Install from the USB

I got the 9000F error when trying a cmd option shift R Mojave downgrade from Catalina beta as well..

To get rid of the error, I connected the MacBook Pro with T2 to a wired Ethernet connection via a USB dongle. That allowed me to use Disk Utility and enter enough passwords to erase the SSD during a command R recovery mode reboot. That then allowed me to recover factory Mojave after another cmd option shift R recovery mode reboot.

The key, after hours of trying, was to use a wired network connection (to Apple servers) instead of WiFi.

For whoever reads this, take it to an apple store and set it next to a display macbook or a place where you can entertain yourself while this process is happening. It will take a while . When you're there, open your laptop and hold "option, command, R" on the keyboard and turn it on. You will enter internet recovery mode. Connect it to the apple store network. It may fail once or twice but I kept trying and it eventually worked. I came in to get it inspected but the wanted me to wait 3 hours because they wanted to replace the logic board. That sounded expensive to me so I just did the internet recovery there by myself. Im running MacOS Catalina. DO NOT get your macbook inspected without trying this method first. It might work for you. I tried this at home and nothing would work. My WiFi connection is stable but it seems that apples in store wifi is much more stable so i recommend trying it in one.

marioorellana's process is pretty much what worked for me.

Yesterday, I spent a couple of hours with apple supprt at the store. They had managed to wipe my drive, which I wanted done, and were in the process of restoring Catalina as we couldn't get it operational with any other OS. It was taking too long and I had to go. When I tried to resume the process at my house it would not work.

This morning I saw Mario's post and I realized my problem might be me trying to use WiFi (Thank you, Mario!). I plugged in to my ethernet and tried a few key combinations. I'm sure it was just the repitition that worked and not the specific combo. OPT + CMD + R is was is what I used. But I tried each of them a few times before it worked. Just be patient.

Also, I selected fresh install of Catalina and after it was all up and running I used the Migration Assistant to do a complete restore from a Time Machine backup from a USB C SSD.

Confirmed for me too, i had the same problem, after many try it worked, with the wifi.

Be patient and repete the process until it work !

I'm in a new place now, by which I mean my MBP is no longer stuck on "26 minutes remaining" and now says "Estimating time remaining...". Should I just wait several more hours?

All - I have the fix - confirmed with two rebuilds.

All you have to do is reset the PRAM twice. Then it will rebuild from either WiFi or Ethernet.

I did this after visiting an Apple Store - then again tried at home.

Apparently its the machine remebering the last OSX.

This was on a Macbook Pro 2018.

After PRAM reset - then Option,Command R.

The timer should show approx 14 mins (If it shows 5 or less it fails to 9000F).

Hope this helps you.