macOS 15.4 update failed on external disk

I’ve had the same problem, except mine is with two different volumes on the internal SSD on my M1 Macbook Pro. My work side updated absolutely fine, but I was unable to update my personal side - it rebooted in a similar way to yours, but then just had an “We ran into a problem” style prompt with the option to report.

As there are a fair few vulnerabilities addressed with this update and I had not rebuilt my personal volume since I got the device, I thought I’d try installing from scratch but I’m hitting the same problem with just trying to install the OS on the separate volume, it doesn’t complete successfully and now I’m stuck with just my work volume.

Planning on doing some more troubleshooting at the weekend when I have some more time, but this isn’t ideal.

I have the same issue and error report. This has happened consistently after trying to install the macOS 15.4 update on an external drive.

Device info:

• M1Pro MacbookPro 14in
• 512 GB internal SSD
• 2 TB external SSD connected via Thunderbolt 3

I have tried:

• Removing my laptop from FindMy
• Turning off SIP on the internal drive
• Downloading and running the full installer to install to the external drive
• Using Recovery to install to the external drive
• Using the bless command from the Recovery mode terminal. (See: screenshot)

So based on the screenshot and my attempt to enable SIP on the external drive after installation failed it looks like a local boot policy is never set due to a preboot error.

Anyone have any luck with a fix?

I've the same problem with M1 MacBook Pro and update on internal SSD.

So yesterday I've downloaded the update from macOS 15.3.2

After the download from Settings it starts to update.

After that it shows a window where it ask for my FileVault password (never seen before).

So, I've inserted it.

After that, only boot loop. No log given.

So, I've seen using Terminal that in Macintosh HD - Data there are all my folders and files.

I've tried:

• Restarting in Safe Mode: same problem
• Create a macOS 15.4 update from USB stick created from another mac: after install, it keeps bootlooping and no log provided.
• Using S.O.S. from Disk Utility it shows a lot of warnings on snapshots.
• Restore window shows "Install Monterey" that is four years old.

So, now, how can I do?

Since this morning I'm with Apple Support but no guidelines to solve the problem.

I don't want to loose all my data for a minor update (I've done a cp operation using Terminal on a external SSD but probably I've missed some path/folder to backup).

I just managed to update my external hard drive to 15.4 after first turning off fire vault. I think I already did that in the past and it failed so it could be that Apple partially fixed the installer

I have the same exact problem on my M1 MacBook Pro.

But no external disk for me, just internal one.

Was updating from macOS 14 and it kept giving me the “your computer stopped unexpectedly” error after reboot…

eventually I manually upgraded to 15.3 but from there 15.4 still won’t install

I have the same problem.

I always installed the OS and on an external disk for testing.

With version 15.4 so far it is not possible. i deleted from scratch both internal and external.

I installed on the internal with UDF procedure. On the external, but also on the internal partition it installs but does not boot from there and gives an error.

I believe it is Apple's fault and they need to fix it immediately before we lose everything.

It's no coincidence that they still haven't released 15.4 in APPSTORE.

This is the same situation I’m in now, with a non-working device and the same select startup drive error you mention after erase and reinstallation. I have an appointment on Saturday with the service center and will provide an update then. Looking at some other threads on discussions, some have advised trying a DFU revive/restore, but you need another mac running 15.X to do that which is not something I have access to currently.

Update after my visit to the Apple Store for a service, they were successfully able to perform a DFU restore via Apple Configurator. Took about 15-20 minutes to complete, and the OS is now installed correctly with 15.4.

When I get home I'll try re-creating my separate volume for work and will begin the setup process for that, and report if it is successful. The technician seemed to think it may be something related to FileVault causing the issue, which may have affected the preboot partition although I'm surprised fully wiping the disk didn't fix that. So if you have access to another Mac running 14/15 with USB-C, you may have success doing a DFU restore. Note this will require the device itself to be wiped. As my device as already wiped the tech did not try a revive which also may have been successful.

That's right with DFU Mode I did it too.

I installed correctly on the internal drive in this way version 15.4. But then on the external drive it could not be installed even though it does all the splitting and copies the files.

After rebooting , when it should have started from the external drive, it starts the system on the internal drive with the error forced reboot due to error ....

Sad to say I've hit the same thing now. While my personal volume is now working fine post DFU, I've just tried to create my work volume again on the internal drive and install 15.4 to that, but I'm hitting the exact same problems again. The tech said it might be FileVault related, so I've also tried disabling that and installing again but it didn't work.

The other main thing that worries me at the moment besides being unable to use this device for my normal work setup, is that if for whatever reason I need to reset my Mac and start again from scratch, I'll need a DFU restore in order to do that since any fresh installation of Sequoia seems to fail, regardless if it's from the App Store, a USB drive or the recovery mode. It's not exactly a quick trip to my local Apple Store either.

Here is related topic Ithink: M1 macbook pro fails to upgrade to Sequoi… - Apple Community

Afraid not, both of my volumes are normal APFS. I've also since tried reinstalling macOS again using the recovery mode and a USB recovery drive, while creating a new volume for personal use without success. I've attached the error log output that I am receiving when it reboots automatically into my work volume after the failed install.

It looks like something is causing a kernel panic during the initial setup after reboot. I've reported it to apple using the built in prompt.