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Ventura 13.4.1 external bootable drive refuses to start

I'm running Ventura 13.4.1 on my 2020 MacBook Air M1. I'd like to keep that installation intact and install Ventura 13.4.1 on an external drive for testing/experimentation. But after running the 13.4.1 installer on the external drive, it refuses to start and complete the installation. Here are the steps I'm following...


  1. I booted to the startup options and set Startup Security to "Reduced"
  2. Format external drive APFS Container with GUID Partition Map
  3. Download Ventura 13.4.1 from App Store and install to the external drive
  4. Once the install is complete, the system restarts
  5. The new installation appears to be booting, but when the wait bar reaches about 50%, the system restarts again. I understand that it's normal for the system to restart more than once during installation.
  6. But then the system keeps restarting. After four or five restarts, it finally boots into the Boot Recovery System and I'm given the choice to either reinstall or choose a different startup drive. If I choose "reinstall", I'm presented a choice of four drives: the internal drive, the external drive (greyed out), and two drives labeled "preboot". When I hover over the external drive, I'm told I can't install to that drive because it has an incomplete installation, and I need to reformat and start over.
  7. So I boot to the internal drive, then in System Settings I try to set the external as the startup drive, but then when I restart I get an error message that the drive can't be set as startup and get a "108" error message.


I'm trying this with two external drives: a Corsair Voyager GTX 256GB and a PNY USB 3.2.2 256GB. I get the same result with both. Both drives have a USB-A connector, so I'm connecting them to the MBA with an Apple USB-A to USB-C adapter.


I actually had Ventura 13.2 installed on the Corsair GTX, and it worked great. But it wouldn't upgrade to 13.2.1, so I erased it to try and do a fresh install, but ran into this same problem, and haven't been able to get Ventura working on either external drive since.


Any suggestions? Is there an error log someplace that might shed light on the problem?

MacBook Air 13″, macOS 13.4

Posted on Jul 3, 2023 3:18 PM

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Posted on Jul 3, 2023 4:58 PM

I got this working by creating a Monterey bootable installer drive, and then using that to install Monterey on my external drive. I was then able to upgrade the Monterey to Ventura 13.4.1, so I think I'm good.


But if anyone has an idea why the direct Ventura installation didn't work, I'd like to know.

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6 replies
Question marked as Top-ranking reply

Jul 3, 2023 4:58 PM in response to schuft

I got this working by creating a Monterey bootable installer drive, and then using that to install Monterey on my external drive. I was then able to upgrade the Monterey to Ventura 13.4.1, so I think I'm good.


But if anyone has an idea why the direct Ventura installation didn't work, I'd like to know.

Jul 8, 2023 7:40 PM in response to xPlanePilot

FWIW called Apple Care and documented that after installing Ventura 13.4.1 (source the apple store),... was able to install a new OS to an external thunderbolt drive,... BUT upon selecting


"System_Settings>General>Startup_Disk"


from the newly installed OS (on and external drive),... and selecting the internal drive on my MacBookPro M1, what I get is an error message that says the OS has to be reinstalled,...


NOTE on my m1 also tried to,... Press and hold the power button until “Loading startup options” appears.


Change your Mac startup disk - Apple Support


BUT this method also failed,... so have to say IMHO that there is a problem that needs to be fixed by AppleSoftWare engineers


Case Number: 102040363400


Jul 5, 2023 11:03 AM in response to schuft

No idea especially since I haven't tried installing macOS to an external drive on an Apple Silicon Mac yet. It is one of the things I will need to try in the very near future.


I do know that Macs are very picky about the drives used for booting, so that is always a possibility for the failure.


It also doesn't help that the Apple Silicon Macs have introduced a new concept of "ownership" which can also complicate things involving external boot drives especially when updating the OS on the external. I don't entirely understand this new "ownership" aspect, but just seen it mentioned a few times when someone tries to update a system with multiple boot drives.


Even on Intel Macs I have seen a Mac not reboot to the external drive to complete phase 2 of the installation. Many times I have had to manually select the external drive to boot so that the installation could complete. I don't know why some Macs are like this....seems to be independent of any specific version of macOS.


If you have rebooted and started phase 2 of the install process and it is interrupted, then you should be able to find the installer log stored on the external drive. I'm not sure where it would be located, but most likely either in "/Library/Logs" folder or "/private/var/log" folder (these paths are in relation to the root file system if the drive booted, not the mount point if accessing the drive from another boot drive which would likely add "/Volumes/<mount-point" to the path. If the install fails before starting to boot into Phase 2, then I don't know if the installer log is still saved there or not. It has been a while since I had to resort to looking for an installer log.


Jul 8, 2023 2:30 PM in response to schuft

FWIW I'm an xPlane user (which is a FlightSim that can be FAA certified) that can run on multiple Macs networked together,...


https://www.x-plane.com/pro/certified/


https://x-plane.helpscoutdocs.com/article/34-using-networked-multiplayer-external-visuals-apps#:~:text=To%20set%20up%20a%20multi,over%20a%20Wi%2DFi%20network.


Anyway FWIW I run xPlane on a MacStudio and make a bootable duplicate of my internal SSD drive using SuperDuper (version 3.75)


https://www.shirt-pocket.com/SuperDuper/SuperDuperDescription.html


After upgrading to Ventura 13.4.1 I can no longer go to "System_Settings>General>Startup_Disk" and boot from a thunderbolt external drive from OWC (where-as before the latest Mac OS 13.4.1 I was able to boot from my thunderbolt external drive


https://eshop.macsales.com/shop/envoy-express/thunderbolt-3


The very legitimate reason I find it necessary to run from external thunderbolt drive(s) is because the flightSim is configured differently (and so I do testing of different aircraft configurations on the external drive and if things don't work, the way I have my various Macs setup which do the various computations for the flight sim physics model and the various external views,... if there is a problem (with a new configuration) I have a stable copy I can fall back up (on the internal SSD drives in my MacStudio/MacMini)


Doing some checking seems other people who upgraded to 13.4.1 also are encountering problems (booting from external drives)


https://apple.stackexchange.com/questions/461724/ventura-would-not-read-sandisk-ssd-after-update


https://forum.parallels.com/threads/boot-failure.360837/


hopefully APPLE software engineers fix this problem soon

Ventura 13.4.1 external bootable drive refuses to start

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