How to Restore BridgeOS on a T2 Mac + Boot a Mac to DFU Mode
News from: Mr.Macintosh
How to Restore BridgeOS on a 2018 /2019/2020 + 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.
- 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)

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)
This link shows the different ways you can boot to the Recovery Partition or Internet Recovery support.apple.com/en-us/HT204904
Typical symptoms that you might see that would indicate a failed or bricked update.
- Mac Seems dead
- Will not turn on
- Black Screen
- No Fan Noise
- Power on LED Light does not turn on (Mac Mini or 2020 iMac)
- 1. Updates
- 2. Warning!
- 3. List of T2 Compatible Macs
- 4. How do I find my T2 Mac BridgeOS Version?
- 5. Setup and Cable Requirements before you begin
- 6. Download Apple Configurator 2 app
- 7. How to Boot your T2 Mac into DFU Mode
- 8. Instructions for the MacBook Pro & Air (2018-2020)
- 9. Instructions for the iMac & iMac Pro (2017 & 2020)
- 10. Instructions for the Mac Mini (2018-2020)
- 11. Instructions for the Mac Pro (2019)
- 12. You made it! Apple Configurator 2 Steps
- 13. Begin BridgeOS Revive / Restore
- 14. Finishing Up
- 15. Can I Downgrade from a Beta Version of BridgeOS to a Production version?
- 16. Troubleshooting DFU Mode & BridgeOS Update Problems
1. Updates – Article Updated 11/17/20
mrmacintosh.com/how-to-downgrade-t2-bridgeos-beta-to-a-production-version/
2. Warning! Please Read
- 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
- 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?
5. Setup and Cable Requirements before you begin
- 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
7. How to Boot your T2 Mac into DFU Mode
Apple’s Instructions
You can find Apple’s instructions for booting into DFU mode here.
8. My Instructions for the MacBook Pro & Air
- 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 Right Shift, 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.
9. Instructions for the iMac (2020) & iMac Pro (2017)
- 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)
- 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)
- 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
- This is what you will see if the Mac is NOT booted to DFU mode.
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!
14. Finishing Up
15. Can I Downgrade from a Beta Version of BridgeOS to a Production version? i.e Bug Sur BridgeOS to Catalina Version?
16. Troubleshooting DFU Mode & BridgeOS Update Problems
- 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.
- 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.
If your Target Mac is on 10.15, then your Host Mac needs to be on 10.15.
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)]
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.
- 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.
Apple Configurator 2 BridgeOS Firmware Download Location.
Thanks MrMacintosh Reader Max C for letting me know the location of the BridgeOS Firmware files.
~/Library/Group Containers/Group.com.apple.configurator/Library/Caches/Firmware
Apple Configurator 2 Log Location
~/Library/Group Containers/xxxxxxx.group.com.apple.configurator/Library/Logs
Note that for version 2.12.1 the log does not seem to be working.
























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