This database will contain download links for macOS 12 full Installer pkg files (InstallAssistant.pkg). This file is the same full installer that you would download directly from the App Store for Intel and Apple Silicon M1 Mac Computers. The InstallAssistant.pkg is stored on Apple’s servers and contains the full “Install macOS.app”. Once downloaded, all you need to do is install the pkg and the full installer of macOS will be in your applications folder. This change was made when Apple revised the full installer for Big Sur. The InstallAssistant.pkg is not available for Catalina or Mojave.
UPDATED: 3/25/24
NOTE:Depending on the browser you are using, you might need to right click and select “Copy link address”. Past this link into a new tab and it should start to download.
NOTE:Depending on the browser you are using, you might need to right click and select “Copy link address”. Past this link into a new tab and it should start to download.
The InstallAssistant.pkg is just a standard package that includes the full macOS 12 installer.app. All the pkg does is install/move the app to your applications folder. Let’s take a closer look.
macOS Big Sur 11.2.3 via SUS Inspector
I am using SUS Inspector to view the full installer for macOS Big Sur 11.2.3. You can see the InstallAssistant.pkg file listed. You can also see the direct download path from Apple’s servers. The link does not last forever. For example, the download link for beta full installers only seem to last for a month or so.
Production links last a little longer. For example 11.2.1 is still available but 11.2 is not. This database will be updated when a new full installer is released.
Thank You
A big thanks to Eric Holtam @eholtam. When I need to verify something in SUS, he always lends a hand!
You can now upgrade or downgrade BridgeOS with an IPSW file and Apple Configurator 2!
You can now upgrade or downgrade BridgeOS on your Intel T2 Mac with an IPSW file & Apple Configurator 2!
As soon as Apple released the very first T2-equipped Mac, MacAdmins wished that they had a way to downgrade BridgeOS. You can now even downgrade BridgeOS on a T2 Mac up to 7 days after an update!
UPDATED: 6/07/22
BridgeOS IPSW Downloads
In the chart below is a list of previous BridgeOS IPSW files along with the signing status. (Signed = You can upgrade or downgrade) All links are Apple Software Update direct downloads.
You can downgrade BridgeOS to one previous version (with in 7 days of a new os update) if you are having issues or would like to test the software update mechanism. The requirement for BridgeOS downgrade is that you need to satisfy the minimum OS Version or newer.
Why would anyone want to downgrade BridgeOS?
Example – You updated to macOS Big Sur 11.2.3 from 11.1. Something in the new version of bridgeOS is causing problems on your T2 Mac. You now want to downgrade to a previous version so you can single out the issue. You will need to downgrade macOS down to 11.2 to support the previous version of BridgeOS. If you downgrade BridgeOS to an older version than the installed OS then macOS Big Sur will not boot and you will be prompted to update BridgeOS from the macOS Update Assistant environment. After downgrading BridgeOS you will need to reinstall/downgrade 11.2 over the top of 11.2.3, or reinstall 11.2. You will now be running 11.2 and the matching bridgeOS version 18P4346.
NOTE! You can only downgrade back one previous version. Apple usually supports T-1*, current minus one version. *Apple will usually leave the previous version of BridgeOS signed for about 7 days after the release of a new update. The BridgeOS signing schedule follows iOS. (Apple will unsign previous versions of iOS about one week after a new update)
How to Downgrade BridgeOS on a T2 Mac
If you would like to learn how to do this, click on the link below!
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.
