Last auto upgrade failed to run after a couple of seconds last week and have been unable to run anything since.
Unable to run Battle.net-Setup.app or upgrade anything.
Have run through all the suggested fixes… re: virus software, background apps etc but can’t get anything to run. (except up grading system to Big Sur which Im trying to avoid)
Im on OS 10.15.7 - everything running fine last week and no changes my end.
Just submitted a Ticket to Tech with system profile, but wondered if I was missing something really basic? (like me being stupid) - doh!
Never had any problems with any Blizzard games or upgrades before. any suggestions greatly appreciated 
Well - updated to Big Sur… and it didn’t make any difference!
Don’t know if this will help anyone? but I solved the problem of Battle.net loading on my machine.
Had a very long “live chat” with a very good tech guy at Apple who ended up going through all my system settings with me, finding something that he thought indicated malware… which I had kinda discounted as I have been running “Bitdefender” for antivirus - but malware had got through both my antivirus and my Firewall .
He advised me to run “malwarebytes"
I advise running malwarebytes if you have a problem running or installing anything.
There is a free test version available, so worth giving it a try!
It found and quarantined 17 malware items in about 3 seconds - and everything started loading and running immediately without a problem.