{"id":47392,"date":"2025-04-11T15:59:36","date_gmt":"2025-04-11T19:59:36","guid":{"rendered":"https:\/\/mjtsai.com\/blog\/?p=47392"},"modified":"2025-04-11T16:01:21","modified_gmt":"2025-04-11T20:01:21","slug":"failed-software-update-on-the-external-drive-of-an-apple-silicon-mac","status":"publish","type":"post","link":"https:\/\/mjtsai.com\/blog\/2025\/04\/11\/failed-software-update-on-the-external-drive-of-an-apple-silicon-mac\/","title":{"rendered":"Failed Software Update on the External Drive of an Apple Silicon Mac"},"content":{"rendered":"

I thought I was out of the woods in setting up new Apple Silicon test macOS systems, after finally working around a Sequoia bug to get old versions of macOS to install on an external drive<\/a>. Then Apple released the first beta for macOS 15.5, and I found that I couldn’t update to it.<\/p>\n\n

After I agreed to the license and entered my password for software update, it would fail saying, “User interaction required. An error occurred while installing the selected updates.” I’ve had lots of problems with the Software Update<\/strong> pane of System Settings in recent years, but the command-line tool had always worked. So I tried sudo softwareupdate -irR<\/code>, but that also<\/em> kept failing, saying: “Failed to authenticate.”<\/p>\n\n

This seems to have been caused by a problem with the LocalPolicy<\/a>. I was aware that ownership<\/a> is an issue with Apple Silicon Macs, but it had never really caused problems for me before. I would just enter the requested information for a prior account when installing macOS, and it seemed to all just work, albeit with some annoying extra steps.<\/p>\n\n

This external Sequoia drive that I was trying to update to macOS 15.5 had been originally created using a different Apple Silicon Mac, so in retrospect it makes sense that the owner information wouldn’t be right for the Mac where I was trying to do the update. But this never occurred to me because the Mac was able to boot<\/em> from the drive just fine. Apparently, the owner account is not necessary for booting but is<\/em> necessary for updating.<\/p>\n\n

A visible symptom of ownership problems seems to be that the Mac won’t auto-boot from the drive. It will either boot from the internal drive or take you to the startup manager. I didn’t notice this because I had been intentionally switching back and forth between different boot drives, always holding down the power key and selecting the drive using the startup manager.<\/p>\n\n

I happened to boot into macOS Recovery and look in the Startup Security Utility<\/a>, and I saw that it did not have access to change the security policy for the external drive. In order to do that, it said I had to set the drive as the startup disk. This kind of didn’t make sense because don’t the security options get set when booted from Recovery?<\/p>\n\n

Anyway, I went to the Apple menu and chose Startup Disk<\/strong> and clicked on the external drive. Then I went back to Startup Security Utility and nothing seemed to have changed. OK, maybe I have to restart and it will use the Recovery from the newly selected startup disk? So I did that but ended up in the same place. It was still acting as though the external drive wasn’t the startup disk, even though I had selected it.<\/p>\n\n

Maybe the startup disk will stick if I click the Restart<\/strong> button that’s in the Startup Disk<\/strong> window<\/em>? That turned out to be the key. When I clicked the button, it showed this error:<\/p>\n\n

This volume does not have any authorized users for this computer.<\/p>\n

The selected system does not have any users that are authorized to administer this computer. You can continue to try to set the startup disk but some features such as software updates will not be functional. If you know the password of one or more users on this system you may authorize the users by clicking on\n“Authorize Users…”<\/p><\/blockquote>\n\n

I don’t know why software update couldn’t tell me this or why there is seemingly no direct GUI command to view or edit the authorized users. But restarting from within<\/em> Startup Disk<\/strong> is apparently the way to get macOS to offer to fix the LocalPolicy. Once I added the user, I was able to do a normal boot from the external drive and software update normally.<\/p>\n\n

Previously:<\/p>\n