Re-install Xcode command line tools (xcode-select --install), then it should work.
Thank you Collin for your timely help.
I had another old Mac to update without any Xcode installation.
I ran this line first - before seeing your reply - and it worked fine.
So anyone who has NO prior Xcode installation should just do this - no need to install the whole Xcode developer bundle!
UPDATE - On the Mac that produced the error sequence in my post #10,694, I totally removed Xcode - at least to the best of my knowledge - following various probably non-definitive online instructions. The last one I tried - which may have been the best to try first - was as follows (note these are for Mojave):
Select > About This Mac > Storage > Manage...
On the left hand side select Applications (near or at top of list)
Sort by name and select Xcode.app then select Delete...
Wait while it uninstalls. It may take a few minutes.
Go to Terminal and enter xcode-select --install (This may not be needed.)
Follow dosdude1's instructions in post #10,677.
I finally have a (relatively) secure, up-to-date Zoom app tested and working.
As a HUGE bonus, I found I also got a much faster, more responsive Mac after uninstalling Xcode.app. This iMac 11,1 now runs faster than it has in years - at least since Sierra in 2016.
I am not a developer (pretty obvious from my posts
), and can't recall for what reason I installed it in the first place. I think it had to do with learning Python and installing Anaconda, which seemed overkill even at the time.
Quite likely, I only ever needed to install the command line tools to make something work that I almost certainly don't now use.