Arduino connected to mac port but sketch wont compile

All,

ive been working with a class of kids on Arduino robot kits from Elegoo. The software has worked all week for this kid but today it won't Compile or Upload his sketch. He can see the USB port but it doesn't seem to recognize the UNO board. he has tried multiple USB ports, restarted Arduino and switched between Beta 1.9 and 1.8 and rebooted the Mac. We can't get even a brand new sketch with nothing in it to upload.

Any help would be appreciated. I cant get to the computer myself due to social distancing.

Steve

Error MessageL:

Arduino: 1.9.0-beta (Mac OS X), Board: "Arduino Uno"

fork/exec /Users/thomas/Library/Arduino15/packages/arduino/tools/avr-gcc/7.3.0-atmel3.6.1-arduino7/bin/avr-g++: no such file or directory
Error compiling for board Arduino Uno.

This report would have more information with
"Show verbose output during compilation"
option enabled in File -> Preferences.

Sounds like the compiler directory is corrupt or missing. If you have the permissions, try reinstalling the arduino software as administrator to get that file back. No clue why it would go missing after it worked fine before....

Thanks Techno. I uninstalled, removed known directories, rebooted and then reinstalled. I’m not sure where the compiler directory is but i deleted everything in the apps, documents Arduino folders.

Unfortunately, he gets the same error message even though sketches open they will not compile.
Arduino: 1.8.13 (Mac OS X), Board: “Arduino Uno”

THE OS IS macOS Sierra 10.12.6 there is enough HD Space to continue writing.

fork/exec /Users/thomas/Library/Arduino15/packages/arduino/tools/avr-gcc/7.3.0-atmel3.6.1-arduino7/bin/avr-g++: no such file or directory
Error compiling for board Arduino Uno.

This report would have more information with
“Show verbose output during compilation”
option enabled in File → Preferences.

Did you delete "/Users/thomas/Library/Arduino15" manually before reinstalling? Not sure why, but the arduino installer doesn't remove that folder and hence never regenerates it unless you manually go in and remove it. It's annoying the way they've done it, but it's how it is

Is the Arduino IDE installed in administration mode? The problem could be the system, deleting the Arduino15 folder.

Make sure you have the Administration permission.

..Arnav