this is what I did to resolve because I had a folder Rosetta sitting in my /Library/Updates folder which seemed to be hindering things, I also couldn't remove SIP to remove the folder and after looking a several different solutions came up with these steps to resolve:
1) removed appleID from the system , system settings/select ID, remove account
2) booted into safe mode, opened terminal and disabled SIP using: csrutil disable
3) rebooted into safe mode and cleared the folders (in my case Rosetta) from 'VloumeName/Library/Updates' leaving just the plist files in there in my case command was sudo rm -R '/Volumes/Macintosh HD/Library/Updates/Rosetta'
4) rebooted again into safe mode and requested update via terminal sudo softwareupdate -i -a -R
5) system rebooted a couple of times
6) logged into **
7) rebooted again into safe mode, then turned SIP back on using csrutil enable in terminal
8) rebooted normally and added my iCloud/appleID back to system
hope this helps you or someone else
cheers
[Edited by Moderator]