Unable to upgrade macOS

Gordon Maynard wrote:

Cannot upgrade from MacOS 26.0.1

I have an M4 Mac Mini which I can't update beyond Mac OS 26.0.1. I have tried MacOS 26.1 . When I run the update the Mac appears to go through the motions of installing but at the end of the process we are still at 26.0.1. I have tried both Software Update and the command line.

The only unusual factor is that I am installing on an external drive which I assume is allowed, this is essential now that it is not possible to upgrade internal drives.

Any help appreciated.

[Edited by Moderator]

dis able any firewall you may have set in >System Settings

Change Firewall settings on Mac

unplug all non-essential peripherals when testing

Uninstall all third party apps that are Cleaners/Optimizers/VPN/Anti-Virus

all known to cause issues on the macOS

try from a A SafeBoot Start up your Mac in safe mode - Apple Support

Login and test.

Call Customer Support (800) MY–APPLE (800–692–7753)

or on line https://getsupport.apple.com/

or call AppleCare Support at 1-800-APLCARE (800-275-2273)

Outside the USA—Contact Apple for support and service by phone

See a list of Apple phone numbers around the world.

Contact Apple Support - Apple Support

So have you checked the internal storage to see if it got updated to 26.1 instead of the external storage? Just a thought. If the internal storage is limited you should consider keeping only macOS on it and moving your data to the external drive.