I have installed the latest VM/VS2019 (yesterday). When loading a program that I've been working on with my older VM/VS2015, it won't compile a program that the older VM/VS2015  (and Arduino 1.8.7 IDE itself ) will compile OK. The new VM version handles a ESP32 sample program OK. I've tried a completely "Stripped-down" version of my program consisting of just the following includes, plus empty/trivial setup(), loop() functions:
#include "FS.h"
#include "SD.h"
#include "SPI.h"
#include "driver/i2s.h"
This compiles OK until  I add the last line (driver/i2s.h), then the compiler gives the following error which strangely references errors in the FS library:
System.IO.DirectoryNotFoundException: Could not find a part of the path 'C:\Users\bmill\AppData\Local\arduino15\packages\esp32\hardware\esp32\1.0.2\libr
aries\FS\driver'.
  That "driver" folder does not exist under the FS folder- but the "src" folder does, and it contains the FS.h and .cpp files needed for the program code (and which older VM/VS must be using)
Adding that last line will require the compiler to get a library from the arduino/hardware/espressif/esp32/tools/sdk/include/driver/driver. Both the Arduino 1.8.7 IDE alone and my older VM/VS2015 find this folder properly and compile without error.
  I'm not experienced in how the VM toolchain picks out the proper library paths to use, but something is different from the way my older VM/VS2015 and the new VM/VS2019 work.
  I added ESP32 support to the Arduino IDE using the boards manager, and have the latest (1.0.2)
  Any ideas?
Thanks in advance.