Unable to boot Macbook M4 from new external drive.
Macbook M4 Pro. Sequoia 15.2
External disk is Samsung T-9 (4T)
Boot/recovery/Security was set to reduced security. No “boot from disk” option in menu.
Erase disk (expanded menu, erased from top of disk).
Formatted APFS with GUID partition.. Name is 7 characters with no spaces or special characters.
Run OS installer from boot up recovery. Install to external disk.
Upon reboot external disk shows volume on disk as “Bootable = Yes" in Disks.
When rebooting and selecting the drive, it spins for a moment and then no change.
If I go to options, select startup disk, I get an error. “The selected version of macOS on the selected disk needs to be reinstalled”.
Upon reboot, looking at the external disk I see the system folders.
My first Macbook and first attempt booting from external disk. I've tried many times. I'm missing something here.
I have also tried this with different SSD drives, different cables, and connected to different ports. Same results.
MacBook Pro 16″