No apps open. Get "You can't open the app 'x' because it may be damaged or incomplete. What???

[GhostMac24]

Came home from dinner last night and my iMac was completely DOA. Nothing would open. One program crashed (Handbrake) and all my app icons were suddenly the old placeholder sheet of paper with an A on it. Everything I tried to open (OS programs, Apple software, 3rd party, etc) got the same "You can't open the app 'x' because it,may be damaged or incomplete". What in the world happened???

Did some searching last night and not sure if it is related but found a thread on the apple forums similar to this and somebody asked if they ran out of memory. Well sure enough, I did. I didn't check to see how much space was on my hard drive before I started but I was transferring an entire season of one of my Big Bang Theory seasons to Apple TV format (using Handbrake) and it appears I ran out of HDD space. Is this a problem with the OS where it freaks out when you try to exceed your HDD size???

I also saw in the thread that somebody was successful creating a new master admin account for the iMac, then delete the old and add it back and then you can set it back up as it was. What???

The good news is I created a new admin account and switch logins to the new one and all the apps work just fine under that new admin account only. Of course, it is like they are new apps so they don't have any of the backup files, mail folders, etc.

Any idea what happened and how to fix?

TIA!!!

FYI......
2017 5K 27-inch iMac 3.4 i5
Mac OS 10.12.6

 

[GhostMac24]

I found yet an0ther thread here on macrumors forums that had a proposed solution?
To paraphrase the other post.......

“ Go > Go to > /var/folders > any folder except for zz (don't touch the zz folder), go into and clear any O, C, or T folders that you can. Empty your recycle bin and then restart. You should be able to open your apps again and see your app icons again.”

Not sure what exactly this does and further, there are several folders with the red dot with white line through it saying “you don’t have permissions to see it’s contents”.

Just want to make sure I’m doing the right thing before I go down a rabbit hole.

I have attached what that var/folders/ looks like........