MacBook Air computer won't Shut Down

any advice with this - it is getting really annoying?

I have the same issue on my apple Mac - I have not changed settings on the firewall - I did check as you siuggested and it is turned on. It appears to be trying to update it but gets 80% of the download done and stops - exactly the same as NBarber2 posted and as below

Hello NBarber2,

To help us get a better understanding of the issue, we’d like to ask a few questions.

1. Did you recently change Firewall preferences on your Mac?
2. You mentioned that the install stopped making progress; have you received any error messages regarding the installation at this time? If so, what did the error say?

The above information will help us determine how to proceed. In the meantime, please check out the following link, which outlines how to review and manage Firewall preferences on Mac: Change Firewall preferences on Mac

Use the Firewall pane of Security & Privacy preferences to turn on the firewall in macOS to prevent unwanted connections from the internet or other networks. Learn how to block connections to your Mac with a firewall.

To change these preferences on your Mac, choose Apple menu  > System Preferences, click Security & Privacy , then click Firewall.

Note: If the lock at the bottom left of the pane is locked , click it to unlock the preference pane.

Please also ensure the correct process is being used to shut down or restart your Mac. This page outlines that process: Shut down or restart your Mac

Thanks!

I should have also added that I am unable to cancel the installation and have left the computer for hours with zero progress. The only way I can shut it off is to pull the plug out.

Not ideal and not happy...