You can now downgrade T2 BridgeOS with an IPSW file and Apple Configurator 2 (for up to one week after the release of a new macOS update)
You can now downgrade BridgeOS on your T2 Intel Mac (2017-2020) to a previous version with Apple Configurator 2!
Ever since Apple released the very first T2 equipped Mac, some users wished that they had a way to downgrade to the previous version of BridgeOS.
The problem?
Updating BridgeOS on a T2 Mac was a one way street. You could only upgrade not downgrade.
Why would anyone want to downgrade BridgeOS?
Downgrading BridgeOS for troubleshooting & macOS Update workflow testing.
Let’s go over a quick example of why you might want to downgrade BridgeOS. You updated to macOS Big Sur 11.4 from 11.3. After the update, you’ve found that something is not working right. The T2 chip handles many things including, fan speed, battery, power, charging & sound (speakers & microphone). So in this example, maybe you are getting audio cracking noise (has happened in the past). Now you thinking that the new version of bridgeOS might be causing problems on your T2 Mac.
The 2nd example is macOS Update testing. If you are a system administrator in charge of updating a large fleet of Mac testing is very important. Part of that macOS Update process is updating BridgeOS. An example of this is if you upgrade a T2 Mac from 11.3 to 11.4. BridgeOS is updated in the process. Now that this T2 Mac is on the latest version of BridgeOS it normally can not be downgraded. Even if you boot back to recovery and install 11.3, BridgeOS will remain the same updated version. Set this Mac on the shelf because you will never be able to take it through a full update process again until 11.5. Now you want to downgrade to a previous version of BridgeOS so you can single out an issue or test the full update process again.
Apple Configurator took care of all the work in both above examples, downloading the prod/final version of BridgeOS for your hardware.
This is different.
We can now download full BridgeOS IPSW Files directly from Apple the same way we do now with Apple Silicon M1 Macs. We can then use the BridgeOS IPSW File to restore/revive BridgeOS to your T2 Mac. The difference here is that Apple WILL stop signing for previous versions of BridgeOS. The signing process follows iOS and is canceled usually about one week after the release of a new update. Apple leaves ONE previous version signed (for 7 days) so you can now downgrade to that version!
BridgeOS and macOS Version Caveats
The first thing to know about BridgeOS is that it has macOS version requirements. BridgeOS supports the macOS version that’s released alongside it. The BridgeOS version also supports previous versions macOS. Let’s go over an example.
After updating to Big Sur version 11.4, you are now are having issues with your speakers (sound processed through T2 chip). You want to downgrade to the 11.3 compatible version of BridgeOS to see if that fixes the issue. You can now downgrade! The only problem is, the 11.3 version of BridgeOS does NOT support newer versions of macOS. You will need to downgrade to the minimum version of macOS that is supported by the version of BridgeOS that you are trying to downgrade to. You now need to downgrade macOS to version 11.3 to support the previous version of BridgeOS. If you don’t downgrade macOS to a compatible version and attempted to boot your Mac, you would be immediately prompted to update BridgeOS. The Mac would boot into “macOS Update Assistant” and would then download the latest compatible BridgeOS update and install it for you.
After downgrading BridgeOS you will need to reinstall/downgrade 11.3 over the top of 11.4 or erase and install 11.3 again. You will now be running 11.3 and the matching bridgeOS version 18P4556.
BridgeOS Version Compatibility Continued
I built a table to help visualize the current situation.
This table shows how BridgeOS version 18P4556 is compatible with macOS version 11.0.1 – 11.3.1. A forced BridgeOS update will be triggered if macOS 11.4 or newer is installed.
NOTE: Point/dot releases (example 11.3.1) may or may not come with an associated BridgeOS update. Big Sur 11.3.1 is compatible with the 11.3 version of BridgeOS
T2 Mac BridgeOS IPSW
MacOS
Signed
Version
Date
5.4_18P4663_Restore.ipsw
11.4
YES
18.16.14663
5/24
5.3_18P4556_Restore.ipsw
11.3
NO
18.16.14556
4/26
5.2_18P4347_Restore.ipsw
11.2.2
NO
18.16.14347
2/25
5.2_18P4346_Restore.ipsw
11.2
NO
18.16.14346
2/01
5.1_18P3030_Restore.ipsw
11.1
NO
18.16.13030
12/14
5.0.1_18P2561_Restore.ipsw
11.0.1
NO
18.16.12561
11/12
The table above lists the IPSW file version and build number. The next section is the maximum minor release that is compatible.
The BridgeOS Version in the 4th section matches what is listed in System Profiler (System Firmware Version), followed by the release date and size.
You can only downgrade back one previous version. Apple usually supports T-1, current minus one version. Normally when a new version of BridgeOS is released the the previous version of BridgeOS is unsigned after 7 days and cannot be installed.
My T2 Intel Mac BridgeOS Download Database –> LINK
1. Download the version of BridgeOS IPSW file that you want to install
2. Boot the target T2 Mac into DFU Mode
3. Connect both Macs with USB-C white Apple charge cable.
4. Open Apple Configurator 2
5. Drag BridgeOS IPSW File over to DFU icon.
6. You will be prompted to Restore or Revive
7. Restore = Click Restore (erases all data)- downgrade BridgeOS (you can then reinstall macOS from Recovery
8. Revive = Click Revive (etains all data) – downgrades BridgeOS (you will need to install previous compatible version of macOS over the top of the current version)
9. Done! You are now on a previous version of BridgeOS.
This is what it looks like to drag a BridgeOS IPSW file over the DFU icon in Apple Configurator 2.
Dragging BridgeOS IPSW file over to Apple Configurator 2
The Restore/Revive menu after dragging the BridgeOS IPSW file over to Apple Configurator 2.
Restore or Revive menu for BridgeOS
This is what happens when you attempt to restore/revive with an unsigned version of BridgeOS.
The System cannot be restored on this device. The system install could not be authorized for this device. The build may not be approved for production installs.
This is the message that you get when you attempt to install an unsigned version of BridgeOS.
Downgrade Big Sur T2 BridgeOS Beta to a Production Catalina version of BridgeOS.
Using Apple Configurator, you can now downgrade T2 BridgeOS Beta to a Production version of BridgeOS.
Downgrading the version of your T2 BridgeOS has never been possible. Developers and customers could only get a NEWER version of BridgeOS when updating or upgrading macOS. The ability to downgrade BridgeOS on a T2 Mac was simply not possible. This new change to Apple Configurator 2 most likely happened between version 2.12 – 2.12.1.
My quick 4 min video on how to boot your into DFU mode + restore / revive BridgeOS.
Deep Dive explanation on how to boot your Mac into DFU Mode + How to Reinstall BridgeOS with Apple Configurator 2 – Mr. Macintosh YouTube live demo.
Table of Contents
1. Why would you want to downgrade from a beta version of BridgeOS?
2. Can you Downgrade to a Lower Production version of BridgeOS?
3. Problems Running Catalina with a Big Sur Beta BridgeOS Version.
4. Closer look at BridgeOS versioning
5. The Big Sur installer is now using DeviceIDs compatibility checks.
6. BridgeOSUpdateCustomer updater
7. How to Downgrade a Beta Version of BridgeOS to a Production Version.
8. The Revive Option (for science)
9. Final Notes
1. Why would you want to downgrade from a beta version of BridgeOS?
Let’s say that you installed Big Sur Beta 6, and are now having a ton of problems. You probably want to downgrade to Catalina so you can work again. The only problem is, you are still on Big Sur Beta 6 BridgeOS version 18.16.12370. Keep in mind, your Mac SHOULD still work fine with this version. An example of this is if you have Catalina 10.15.6 installed on your Mac, your BridgeOS version is 17.16.16610. Let’s say that you need to test something on version 10.15.3. After installing Catalina 10.15.3, your BridgeOS version will NOT be downgraded to the period correct version of 17.16.13050. It will run just fine on the 10.15.6 version of 17.16.16610 BridgeOS. The same is the case if you have a Big Sur Beta version of BridgeOS and you downgrade to Catalina.
2. Can you Downgrade to a Lower Production version of BridgeOS?
If you are running macOS Beta, then you can use Apple Configurator 2 to downgrade your T2 BridgeOS to a final or production version of BridgeOS.
What about if you are running a production version of macOS? You can downgrade BridgeOS with Apple Configurator 2, but only for 1 week after a new macOS software update. Apple will unsign the previous version of BridgeOS along with previous iOS updates.
3. Problems Running Catalina with a Big Sur Beta BridgeOS Version.
Let’s say after you downgraded from Big Sur Beta to Catalina 10.15.6, you are now having problems. You might start to see weird issues or crashes? Normally you would have to wait until the next beta or the production version of Big Sur to get a stable version of BridgeOS on your Mac.
Looking at the xml file, I need to find my 2019 16″ MacBook Pro. Regular Model Identifiers or BoardIDs are not used here. You need to find the iBridge ProductID. Below is a snippet of the above .xml file. Below the version of BridgeOS = 17P6610
5. The Big Sur installer is now using DeviceIDs compatibility checks.
A change to the macOS Installer Beta was noticed by @grahampugh. He noticed that the new Big Sur installer now looks at the Mac DeviceID for T2 Systems and BoardID for older 2017 and below Macs.
6. BridgeOSUpdateCustomer updater
Now that we have the DeviceID, how do we know which version of BridgeOS is compatible for this model? The xml file gives us a clue BuildVersion 17P6610. I am used to keeping track of the BridgeOS Boot Rom version which is listed like this 17.16.16065.
The BuildVersion/BuildNumber is located inside the BridgeOSUpdateCustomer > BridgeOSUpdateCustomer.pkg > BuildManifest.plist.
BuildIdentities
ApBoardID 0x3E ApChipID 0x8012 ApSecurityDomain 0x01 Info
Apple Configurator 2 offers two options to Reinstall/Downgrade BridgeOS. Only the Restore option will help you downgrade and stay on the Catalina specific version.
Restore = ERASES YOUR HARD DRIVE + Downgrade BridgeOS
If you want to downgrade to macOS Catalina and a Catalina version of BridgeOS, the fastest way is to use the Restore option. Once the restore is complete, you will be on a the Catalina Production Version of BridgeOS and will have empty hard drive. You can now use Internet Recovery to reinstall macOS Catalina.
What happens if you chose the Revive option?
8. The Revive Option (for science)
As noted above, you have no real reason to use this option. But for science, what would happen? If you are on Big Sur Beta want to downgrade T2 BridgeOS Beta using the Revive option, you will leave your Mac in a non bootable state. This is because you are now running a BridgeOS version that is OLDER than the required Big Sur Beta BridgeOS. The good news is, your T2 Mac is smart enough to repair itself! As soon as the revive option finishes, your Mac will boot to a flashing folder alert or the Internet Recovery boot menu. If it boots to the flashing folder, just boot to Command Option R or Command R and you will get the menu below.
Internet Recovery Boot Menu
Connect to the internet and let it continue. You will be brought to a message that says,
You will get this message as soon as you are booted to the Internet Recovery environment.
A software update is required to use this startup disk.
Click Update and your mac will download the correct build of Big Sur Beta BridgeOS.
On this screen your Mac is updating Bridge OS to a Big Sur compatible BridgeOS.
Once complete, the Mac will boot back to Big Sur. The only way to avoid this would be to boot the Mac to Target Disk Mode so you could erase the drive and reinstall Catalina. That’s why if you want to have BridgeOS and Catalina on the same version the Apple Configurator RESTORE option is the way to go. Just make sure to backup everything before you start as all data will be lost.
9. Final Notes
It should be pretty rare that you should ever need to downgrade BridgeOS from a Beta version. Keep in mind this will ONLY work for beta versions. As I noted above you can’t downgrade from a 10.15.6 version of BridgeOS to say a 10.15.3 version. With that said I would love to be able to downgrade to a previous version. If it’s your job to test OS Updates, once you update one test T2 Mac it’s done. It will not perform the BridgeOS update again until the next update. I really like that Apple let’s us downgrade from a beta version of BridgeOS, the more ways for customers to fix their devices the better! A big hat tip goes out to Mr. Macintosh reader thomas089 for first testing this and commenting in my main article!
This problem can happen to a very small number of T2 Macs after installing the 10.15.4 Supplemental Update.
Did you Install the 10.15.4 Supplemental Update on your T2 Mac, only to find that it will not power up after the Install?
When reporting on issues, I always try to quantify the issue in terms of how many users could be affected. In this particular case, the numbers are very low. This article is to help you rescue your Mac. The issue only affects T2 Macs that have installed the 10.15.4 Supplemental Update. The amount of users reporting this is very small, but the problem can be devastating if the user does not understand what happened or how to fix it.
This issue is similar to the 2019-001 Security Update last November that cause Data loss. The Reports are very close as it was first thought that the problem was the users fault for shutting down the Mac during the BridgeOS update.
What actually happened was, the BridgeOS Update Failed and destroyed the encryption keys.
6. Why write about something that affects such a small number of Macs?
7. Wait a few days before installing updates.
8. Should I block the 10.15.4 Supplemental Update?
9. Does Apple Know about this issue and are they working on a fix?
10. Links
11. Credit & Hat Tips
1. Affected Mac Models
This issue covers almost every single T2 Mac Model. I have not seen any reports of this happening to the iMac Pro 2017 or the Mac Pro 2019.
1. MacBook Pro 16′ 2019
2. MacBook Pro 13″ & 15″ 2018-2019
3. MacBook Air 2018-2020
4. Mac Mini 2018
2. Affected OS Versions
This issue affects only one macOS update.
macOS Catalina 10.15.4 Supplemental Update (19E287) Released 4/8/20
3. Problem: 10.15.4 Supplemental Update Bricked
One of the very first reports was in a MacAdmins Channel. The report said that the user called the helpdesk saying the update hung. Now the Mac does not power on.
Another report from a user with a 2018 13″ MacBook Pro
I attempted to install the update but about halfway through my computer shutdown and it bricked my 2018 13 inch MacBook. No power, no fans coming on and off or anything when pressing and holding the power button.
Another Report from a 16″ Macbook Pro 2019 User.
Confirmed; this is what happened to my 16″ after this install. I needed to do a DFU restore (using Apple Configurator 2 — you can download it to your hopefully spare MacBook from the app store) to get my mac back up and running. Unfortunately, for some reason, after the DFU restore, my 16″ came back up to do a full reinstall, and I had to restore my files from backup.
One More report form a 13″ MacBook Pro User
Anyone else do the recent 10.15.4 update and have their machine completely bricked? Mine will not turn on…not after resetting the SMB…not at all. Apple’s update appears to have completely killed my macbook. It’s now completely unresponsive.
Macbook Air 2018 User
Thursday evening my wife’s Air still showed the update in System Prefs and clicked to install it. She said the dialog box said it was normal for the screen to go black, but it didn’t say it’d never come back!!! Her less than 18 month old Air is now officially bricked. Unresponsive to all attempts to remind it of its mission on earth. A stellar machine until that fateful click.
4. Problem Description
Apple’s T2 Security chip runs software called BridgeOS. That software is updated each time you install a Catalina Update or Security Update. The T2 controls many aspects of your Mac.
The Apple T2 Security Chip is Apple’s second-generation, custom silicon for Mac. By redesigning and integrating several controllers found in other Mac computers—such as the System Management Controller, image signal processor, audio controller, and SSD controller—the T2 chip delivers new capabilities to your Mac
After reading through a bunch of reports the problem seems happen during the BridgeOS Update phase. Most users say that all they saw was a black screen and the Mac was unresponsive. From the users who contacted me over email, after the update failed the Mac was already be in DFU mode. A few users stated that as soon as they connected the dead Mac to a host mac with Apple Configuartor 2 running, it immediately showed up in RECOVERY Mode.
5. Can the dead Mac be brought back to life? YES!
In almost every case, a DFU Mode BridgeOS Reinstall brought these dead Macs back to life!
I wrote a detailed article on how to perform the restore below.
I knew something was up on April 10th two days after the supplemental update was released. I noticed a spike in traffic to my BridgeOS Restore article. Emails and comments started to roll in. They all mentioned that they found the article after the 10.15.4 Supplemental Update bricked their Mac.
6. Why write about something that affects such a small number of Macs?
Like I mentioned at the top of this article, I usually will only report on issues that affect a large number of Mac Users. The idea is that small fluke type issues happen all the time. Usually the user can just reinstall macOS and be up and running.
This case was different. I decided to write this article after reading some of the stories.
Haven’t talked with Apple’s help team since 2004—today we spent 2 hours on the phone—we tried every method to get my bricked 2018 15” MacBook Pro to boot. Hopefully this issue is a small epidemic and not a pandemic; the MBP became unresponsive today while updating to 10.15.4. The last thing I saw before the MBP went quiet and the screen went black was, “about 14 minutes remaining”. Apple Help quoted $815 to ship it to them for a diagnostic and repair. I explained it was working perfectly well before the update—CSR elevated it to a senior who is starting with a new charger and cable.
Here is another direct quote from a 2018 Mac Mini User that I found tonight.
Any one else experienced this problem? Mac mini late 2018. Update went through, restarted Mac and now bricked. Will not turn on at all. Took it to Apple store and they say main board needs replacing at cost of 400usd.
I hope this article finds you mattoneill2! ^
If this article can save just a few Mac Users from having to spend $$$ for a repair, then it was definitely worth it.
7. Wait a few days before installing updates.
A good tip for you is to just wait a few days for the dust to settle before installing updates.
This is not the first time Apple has pulled an update. They pulled High Sierra and Sierra 2019-002 Security Update this past March. It’s a good idea to wait at least a few days before you update.
8. Should I block the 10.15.4 Supplemental Update?
Maybe
The only reason I say maybe, is that the supplemental update does not include any Security Related fixes. Take a look at the list below.
Fixes an issue where Mac computers running macOS Catalina 10.15.4 could not participate in FaceTime calls with devices running iOS 9.3.6 and earlier or OS X El Capitan 10.11.6 and earlier
Resolves an issue where you may repeatedly receive a password prompt for an Office 365 account
Fixes an issue where MacBook Air (Retina, 13-inch, 2020) may hang in Setup Assistant or when disconnecting and reconnecting a 4K or 5K external display
Resolves an issue where a USB-C port in your Mac may become unresponsive
If you need any of the above fixes, then I would say deploy it. The risk is really low.
9. Does Apple Know about this issue? Are they working on a fix?
Unlike the GPU freezing issue or the Wake from Sleep issue, I do not have any information.
How to Restore BridgeOS on a 2018+ T2 Mac using Apple Configurator 2. How to Boot your Mac into DFU Mode
Did a macOS Update Brick your T2 Mac? I will Show you how to Boot your Mac into DFU Mode so you can Restore BridgeOS.
This article will go over how to restore BridgeOS on your T2 Mac. This is not something that you will ever normally have to do. Restoring or reinstalling BridgeOS firmware would only be needed in the following situations.
1. Failed macOS Upgrade
2. Failed macOS Combo or Delta Update
3. Failed macOS Security Update
4. Failed macOS Reinstall
5.Failed BridgeOS or Failed Firmware Update
6. “Command Option R” fails to boot your T2 Mac to the newest version of macOS Internet Recovery. (Example: 10.14 is out but the Mac boots to 10.13)
2. Warning about “Restore” Full Erase! Please Read
The new version of Apple Configurator 2 (2.12.1+) and newer has different options!
Actions > Advanced > Revive Device = Reinstall BridgeOS Only – Revive should be the first option to try. If a Revive does not work, move to the second option Restore.
Actions > Restore = Reinstall BridgeOS & ERASE OS AND USER DATA! – This option will reinstall BridgeOS and erase the SSD. This option is for more serious issues where the Mac does not respond after installing an update.
3. List of T2 Compatible Macs
This is a list of T2 Mac that you can can have BridgeOS restored.
2019-2020 16″ MacBook Pro
2018-2019 13″ & 15″ Macbook Pro
2018-2020 MacBook Air
2018 Mac Mini
2020 iMac
2017 iMac Pro
2019 Mac Pro
4. How do I find the BridgeOS Version on my T2 Mac?
From support.apple.com/en-us/HT203001 – “Choose Apple menu > About This Mac. This opens an overview of your Mac, including your Mac model, processor, memory, serial number, and version of macOS. To see the greater detail provided by the System Information app, click the System Report button.”
About my Mac > System Report > BridgeOS version = 17.16.10525
5. Setup and Cable Requirements before you begin.
You will need to meet the following requirements –
(The Host Mac will do the work and the Target Mac is the Mac you need to Restore)
1. USB-C Mac as the Host Machine.
2. The Host Mac must have at least macOS 10.13.5 and Apple Configurator 2.6 or newer installed. (Version 2.12.1 is the latest)
3. The Host Mac Must be on the same OS version as the Target Mac that you want to Restore. (Example – If the Target Mac is on 10.15 you will need the Host Mac to be on 10.15. If the Host Mac is on 10.14 you will get an error 10)
3. Internet access on the Host Mac – “You may need to configure your web proxy or firewall ports to allow all network traffic from Apple”
4. USB-C to USB-C Cable – The white Apple USB-C Charge will work fine.(USB-C Cable MUST Support Power & Data). Apple notes that a Thunderbolt 3 to Thunderbolt 3 cable is not supported but I’ve tested it and it works fine.
5. The Host Mac can have the cable plugged in anywhere.
6. The Target Mac MUST have the USB-C Cable Plugged in to the Left Hand side USB-C port. This is First port in line (Port closest to the front of the Mac or trackpad) If you are still confused look at the picture below.
If you don’t meet all the prerequisites booting to DFU Mode or BridgeOS Upgrade might fail.
6. Download Apple Configurator 2
Download Apple Configurator 2 app. Version 2.6 or higher is required.
If you do not have Apple Configurator 2, you can download it now from the Mac App Store with this link.
With all the startup keyboard commands you can issue a Mac, booting into DFU Mode should be pretty simple right?
NOPE!
You have to follow a very particular sequence to get this to work. I have attempted to find the exact way to get this to work every time. Even then sometimes the system will refuse to Boot into DFU mode.
Me trying to get my T2 Mac into DFU mode without turning it off or booting into macOS.
Apple’s Instructions
You can find Apple’s instructions for booting into DFU mode here.
Apple’s instructions for booting your T2 MacBook Pro into DFU mode. Image: Apple Inc
8. My Instructions for the MacBook Pro & Air
Bottom line, it’s hard to get your T2 Mac into DFU mode. You could try Apple’s instructions 10 times and STILL not get into DFU mode.
Once you have meet all of the pre requisites above, follow the instructions below to get into DFU Mode every time.
1. The Target Mac must be OFF to begin.
2. Press the Power button and hold for 1 second.
3. While STILL holding power immediately hold down RightShift, Left Control and Left Option.
Hold down all 4 keys for 8 Seconds (count 1 one thousand) then let go of all keys.
You will not see anything on the Target Mac screen.
Keep an eye on the Host Mac’s Apple Configurator 2 Application. The App should say “Connect Devices”
When the Target Mac is booted into DFU mode correctly, the host will show a big DFU icon in Apple Configurator 2.
After you see the DFU picture pop up on the Host Mac you can let go of the keys.
DFU T2 Booting Instructions – Make sure the Mac is OFF. Hold down power for 1 second then also hold Right Shift, Left Control and Left Option for 8 total seconds then let go.
9. Instructions for the iMac (2020) & iMac Pro (2017)
The iMac 2020 & iMac Pro 2017 are a little different yet are super simple to get into DFU Mode.
1. Disconnect the power cord from the iMac Pro or Mac Mini.
2. Plug USB-C/Thunderbolt cable into the USB-C port next to the Ethernet Port.
3. Plug the other end into the Host Mac.
4. While holding down the power button, connect the iMac Pro or Mac Mini to power and continue to hold the power button for about 3-5 seconds
5. You should now see the DFU logo on the Host Mac.
10. Instructions for the Mac Mini (2018)
The Mac Mini 2018 instructions are close to the iMac Pro but the USB-C port that you need is next to the HDMI port instead of the Ethernet port like the iMac Pro.
How to boot a Mac Mini 2018 into DFU mode to restore BridgeOS – Image: Apple Inc
1. Disconnect the power cord from the Mac Mini.
2. Plug USB-C/Thunderbolt cable into the USB-C port next to the HDMI Port.
3. Plug the other end into the Host Mac.
4. While holding down the power button, connect the Mac Mini to power and continue to hold the power button for about 3-5 seconds
5. You should now see the DFU logo on the Host Mac.
11. Instructions for the Mac Pro (2019)
The Mac Pro 2019 instructions were just added to the DFU instruction guide.
How to boot a Mac Pro 2019 into DFU mode to restore BridgeOS – Image: Apple Inc
1. Disconnect the power cord from the Mac Pro.
2. Plug USB-C/Thunderbolt cable into the USB-C port farthest from the power button.
3. Plug the other end into the Host Mac.
4. While holding down the power button, connect the Mac Pro to power and continue to hold the power button for about 3-5 seconds.
5. You should now see the DFU logo on the Host Mac.
12. You made it! Apple Configurator 2 Steps
The hard part is now over. Now we can restore BridgeOS on the Target Mac. When you first open Apple Configurator 2 the screen will look like this.
This is what you will see if the Mac is NOT booted to DFU mode.
Once your Mac is booted to DFU mode, you will see this screen on Apple Configurator 2. You are now ready for the next step.
When you see a big DFU icon when your Mac is properly booted into DFU Mode.
13. Begin BridgeOS Revive
You are now ready to restore BridgeOS on the Target Mac. Click Actions > Advanced > Revive Device.
(DO NOT CLICK RESTORE YET) Only run Restore if Revive does not work. (Restore Erases your Hard drive!!!!!!!)
You will now see a warning message. Do you want update “iBridge” to the latest firmware version? You cannot undo this action. This means that once you update BridgeOS/iBridge you cannot go back to the previous version.
An updated Apple support document shows that we now have 2 different options.
Actions > Advanced > Revive Device = Reinstall BridgeOS Only
Actions > Restore = Reinstall BridgeOS & ERASE OS AND USER DATA!
AC2 version 2.11 – 2.12.1 ??? New Message that warns that the BridgeOS Restore will ERASE ALL OS AND USER DATA!
The message below is what you will see on at least AC2 version 2.10 and below. OR if you click Revive instead of restore.
AC2 Version 2.10 and below – Do you want to restore and update “iBridge” to the latest firmware version?
Click the Restore Button to begin. Step one will download the latest BridgeOS update from Apple.
Step 1. Downloading the latest BridgeOS from Apple.
Step 2. Unzipping BridgeOS
Step 2. Unzipping the BridgeOS Update.
Step 3. Installing BridgeOS Update.
Step 3. Installing BridgeOS
14. Finishing Up
If you would like to see more information you can click View and see a new activity window.
Apple Configurator 2 Activity window.
The entire process will only take about 4-10 Minutes. Most of the time is spent downloading the 400-600MB BridgeOS Update. The Unzip and Install parts only take about 1 minute each. When complete the Mac will automatically Boot up.
NOTE: with version 2.12.1, the entire process may never finish correctly and get stuck at the final part (probably a bug). Once your Target Mac is at the login window the restore is complete. The error that you might see is 0xFA5 (4005)
15. Can I Downgrade from a Beta Version of BridgeOS to a Production version? i.e Bug Sur BridgeOS to Catalina Version?
Let’s say that you installed Big Sur Beta 6, and are now having a ton of problems. You probably want to downgrade to Catalina so you can work again. The only problem is, you are still on Big Sur Beta 6 BridgeOS version 18.16.12370. Keep in mind, your Mac SHOULD still work fine with this version. An example of this is if you have Catalina 10.15.6 installed on your Mac, your BridgeOS version is 17.16.16610. Let’s say that you need to test something on version 10.15.3. After installing Catalina 10.15.3, your BridgeOS version will NOT be downgraded to the period correct version of 17.16.13050. It will run just fine on the 10.15.6 version of 17.16.16610 BridgeOS. The same is the case if you have a Big Sur Beta version of BridgeOS and you downgrade to Catalina.
The answer is YES, follow the link below for an explanation.
I can’t get my Mac to boot into DFU mode. This is the toughest part of the whole process as I mentioned above. Keep trying the steps I listed above. Sometimes it takes multiple attempts to get his to work.
You can use System Information to see if the USB-C port lists your Mac in DFU Mode.
System Information showing a Mac plugged in booted to DFU Mode.
BridgeOS Restore Error 79- The OS Cannot be restored on this device. The Operation couldn’t be completed. (AMRestoreErrorDomain error 79 – Failed to handle message type StatusMsg) [AMRestoreErrorDomain – 0x4F (79)] – If you get this error it means that the BridgeOS update has failed and is unable to complete. The system will be unable to boot. When powered on the screen will be black. The Mac will have to be brought to an Apple Store for Service.
BridgeOS Restore Error – The OS Cannot be restored on this device. The Operation couldn’t be completed.
BridgeOS Restore Error 10 – The BridgeOS Restore failed! This is most likely because the host Mac was 1 or 2 OS Versions behind the Target Mac. The Host and Target Mac need to be on the same OS Version.
If your Target Mac is on 10.15, then your Host Mac needs to be on 10.15.
The OS Cannot be restored on this device.
The operation couldn’t be completed. (AMRestoreErrorDomain error 10 – Failed to handle message type StatusMsg) [AMRestoreErrorDomain – 0xA (10)]
BridgeOS Restore Error 10 – The Host and Target Mac need to be on the same OS Version.
Host Mac and Target Mac Disconnected during restore. – Error 4005
The OS Cannot be restored on this device.
Gave up waiting for device to transition from RestoreOS state to BootedOS State. [com.apple.MobileDevice.MobileRestore – 0xFA5 (4005)]
BridgeOS Restore Error 0xFA5 (4005)
This error will come up when the restore process has been interrupted.
Or, you might get this using Apple Configurator 2 version 2.12.1, as the process never seems to complete properly. If the Target Mac awakes to the login window the process is complete even though the progress bar is at 100%. After unplugging the USB-C cable you will get the error above.
Apple Configurator 2 Reports RECOVERY instead of DFU Status.
Apple Configurator 2 Reports RECOVERY instead of DFU Status.
If you see RECOVERY this means that BridgeOS is unable to boot and is the default status when you power on the Mac.
Failed BridgeOS Restore due to OS Version Mismatch! The Target Mac is a previous OS i.e 10.14 trying to restore a 10.15 Mac, the update will fail with an Error 10
If the Mac already failed the Upgrade, it could already be in this status. If so, you can attempt a BridgeOS restore.
Configurator could not perform the requested action. Apple Controller devices do not support this action.
This means that you selected Actions > Update, which is not supported. You need to select Actions > Advanced > Revive Device
Apple Configurator 2 BridgeOS Firmware Download Location.
Thanks MrMacintosh Reader Max C for letting me know the location of the BridgeOS Firmware files.
