"Available Updates have Changed" lead to failure to install an Update in App Store
Hello:
I upgraded my Mac (21.5 inch Mid-2011) from El Capitan (10.11.6) to High Sierra (10.13) last week. Since then 4 updates have been automatically downloaded (2 iTunes and one Safari, 1- Garage Band) to the AppStore and I successfully installed them. The OSX shows as 10.13.6 in the About this Mac There is now 1 Update Available in the AppStore, showing as a Software Update (restart required) named "Security Update 2020-005 10.13.6".
Here's the problem: when I click on Update or Update All, a window pops open saying "Restarting Your Computer Your computer will restart in XX seconds to install updates" The clock counts down and when time expires a new window appears titled "Available updates have changed" and the only options are either Cancel or Show details. Show details takes me back to the update page, and then when I try to update, this same cycle repeats. I've Restarted the computer and then tried to update to no avail.
I see on the Apple Security Updates page: https://support.apple.com/en-us/HT201222 there is a hypertext link to an update released on 24 Sep 20 for this Security Update 2020-005 10.13.6.
Is there a way to install this Security Update to this Mac?
Thank you for whatever light you can shed on this problem.
iMac 21.5″, OS X 10.11
