I got the prompt to install the latest Arduino IDE (1.8.13). I did and my program broke on the 2nd line:
#include <Arduino.h>
#include <SysCall.h>
With:
C:\Projects\Fluke\Cell 2\Embedded\RelayController\RelayController.ino:1:21: fatal error: SysCall.h: No such file or directory
compilation terminated.
I'm using a Teensy 3.5 and install TeensyDuino after the install. There is very little about an error like this but that I'm using SdFat-master might be a clue? I've uninstalled and reinstalled different versions of the IDE (.10, .11, .12) with no success. I've upgraded before and never had a problem.