macOS 15.4 update failed on external disk

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.

Hi,

I have similar problem on my 14" MacBook Pro M1 Max 2021...

Error message with "panic" message after upgrade to latest Sequoia. So I decided to do full recovery to only available Sequoia.

Recovery started normally, restarts automatically and after reboot it displays dialog to select startup drive. When I select Macintosh HD it says that system must be reinstalled.

I tried erase disk, erase Mac, installation on external SSD with the same result.

Apple support told me that only solution is diagnostic on service center. But I don't think my HW is faulty. It worked fine until latest Sequoia update.

Do anybody make any progress with this issue please? Do you have any information from Apple about it. Do they some inquiries regarding this behaviour?

Thanks

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.

Falko Zurell wrote:

I've got a maybe somewhat odd setup here. MacBook Pro M2 Max with macOS Sequoia 15.4 running on the internal SSD (APFS, encrypted). In addition I have an external NVMe SSD (Samsung T7) where I've also installed macOS Sequoia to be used as StartUp-Disk if need be. With that setup I keep my private and my corporate macOS installations physically separated. "Just" using the same MacBook Pro to run them.

Now I tried to apply the latest update from macOS 15.3 to 15.4 on my external SSD. The update shows, the external disk is set as StartUp Disk and the update process starts. It looks like it does the update with multiple reboots and all. But after it's finished and log in to the macOS it still shows the update 15.4 as available. There were no apparent errors during the update process. But I noticed that wen I log in after the update the system complains that it was improperly shut down and whether it should report that.

Any idea how to debug this? The update worked just fine on the internal SSD without any issue.

M1 Mac mini. Lost a tb of external drive o was running os off for 3 years. Today I got 15.3.1 installed. Same thing happens on 15.3.2 I beleive. 15.4 I have attempted several different things, and still starts up saying is restarted error. I’m not installing on the onboard drive till there’s a fix. Ordered me another ssd so I have one try try updates first in the future. Set my work back a few days.

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.

I ended up going to 15.3.1. my drive was up to date, and 15.3.2 never showed. only 15.4. m1 mini. I also just tried signing out of iCloud on each drive, and installing on internal/external. same error. guess Ill wait till 15.5, and try again.

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 have the same problem. I am running a rented M2 Macbook Pro with an external Samsung Nvme 2TB Disk via Thunderbolt 3.1 and I am unable to install the newest update of MacOs Sequoia 15.4.1.

I am beginning to regret having installed Sequoia at all, the previous Sonoma and Ventura worked well and now there is only chaos. I have had some Time Machine issues as well, and GarageBand Sound Library is not loading and GarageBand itself is also warped. It's very demoralising. I hope Apple figures this out soon. It's unnerving to have such an unstable system!

Same Issue Also having Issues with M2 MacBook Pro,

I still can't install 15.4.1 ?? Runs but then restarts without change.

Also I had made an emergency disk with Sequoia 15.3.1 It will not update to 15.4.1?

The same issue, the built-in version is 15.4.1, the external version 15.3.2 cannot be upgraded to 15.4.1. The upgrade process requires entering a password, and it seems to be completed, but after entering the desktop, it is still 15.3.2, with no error prompts.