macOS 15.4 update failed on external disk

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

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.

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.

Well glad to see there are a number of us with unusual setups.

Mine is Mac mini M2 Pro, bootable from external drive.

As with others, the internal drive updated to 15.4 no problem (as did my backup M2 Mini), but not the external drive. In 2 profiles, I have tried updating multiple times, in standard mode and safe mode. On the spare profile it goes through the procedure, but afterwards still on the old version, on my main profile I get the dialogue box saying my Mac has restarted after a problem.

I'm not sure what factors led to the successful update. My steps were as follows to successfully update the external disk to macOS 15.4:

1. Upgrade the internal disk to the latest macOS, which was 15.4 at that time.

2. Turn off the FileVault for both the internal and external disks.

3. Boot in the internal disk and download macOS Sequoia 15 from the App Store, then install it on the external disk.

(Note: Make sure to download and install 15.4 from the App Store on the internal disk. Doing it on the external disk will fail.)

Last update from me, the release of 15.4.1 has resolved my issue for my dual internal volumes. Both are now up to date on 15.4.1, one upgrading from Sonoma 14.7.5 without any error messages. Both volumes also had FileVault enabled during the upgrade process. I hope that everyone else also has success with their external volumes - I am unable to test this currently.

I had the same problem upgrading a second boot partition on the internal SSD to 15.4 (multiple failures) after upgrading the primary boot partition to 15.4. The solution was to use 15.4.1.

I upgraded the primary successfully to 15.4.1, then booted into the secondary and upgraded it to 15.4.1. Worked fine the first time.

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!

I have 15.4 on my internal drive APFS. I made two external TB drives as boot drives (clone of my internal) and no issue using neither one. All my external drives are APFS with FileVault on.

my problem is after upgrade to 15.4, my M4 Mac mini can't boot from external SSD , it just shows a blank screen and keep reboot for a while. I have reinstalled the OS, and still get a blank screen.

I have a same issue macOS Sequoia 15.4 during installation on External drive but in internal drive no issue

i think that it has installer bug

we hope Apple fix this issue

No issue here. I've done two different external drives and all installs no issue and both boot fine using 15.4. My external drives stared with 15.3.2 before updating.