We have been progressively upgrading the MacMini 2 OS. An upgrade was installed and we tried to install the next upgrade but the MacMini does not recognise that the previous upgrade has been installed so we are stuck.
Does the user mean this computer ?
Has the computer been restarted since the initial upgrade and prior to attempting to install a subsequent next upgrade
To check if the first upgrade has been registers as being installed
In Finder >> Go >> Utilities >> System Information
Left Sidebar >> Software >> Installations
On the Right Panel check and see what version(s) of macOS have been successfully installed
In my listings, macOS 15.6.1 was successfully installed 2025-08-21 @ 03:43 AM
What I do know, from personal experience
When I purchased the M2 Mac Mini back on Oct 22, 2023 - Stock 8 GB Unified RAM and 256 GB SSD
Use it, strictly for Live Streaming on HD TV in livingroom
It arrived with macOS 13 Ventura 13.4 ( 22F66 )
It is currently in usage for the same purpose
Successfully upGraded to each and every version of macOS 14 Sonoma and macOS 15 Sequoia
Depending on your configuration visa vie SSD Capacity versus Empty Space remaining on the drive
Is it possible and hopefully not, the latest upGrade failed with an Error message
Something like " Not Enough Disk Space " ?
Generally the error message may not be presented
It will just refuse to upGrade, ergo does not register the latest upGrade ?
+1
To identify the Mac mini model, see > Identify your Mac mini model - Apple Support
For some additional tips on updating, see > Update macOS on Mac - Apple Support
Mac mini 2 not recognising Mac OS upgrade
