Thanks for the info. It looks like you have switched off "vMicro>Compiler>Deep search for libraries". Arduino 2 always has that setting on. You also have debug enabled which is better Off if you have a compile problem.

I suggest switch deep search back on then try the build again.

Thanks, visual micro should always be same or faster build than arduino. After the error is solved you can switch deep search off again if you don't see an error. (The deep search also ensures automatically inserted prototypes are inserted at the correct location)

If same code between both IDE's then my intial thoughts are that the library resolver is finding different libraries to arduino. Normally, if all paths are the same then that should only happen if two libraries are installed that contain the same headers. Then it is hit and miss as to which is resolved. but lets' see exactly...

The verbose output from the arduino ide would help. That can be enabled in the arduino ide with file>preferences>compile verbose.

These are the libraies that vm is finding:-

Using library Update version 2.0.0 in folder "E:/Software/Arduino/Arduino%20Sketches/libraries/Update"
Using library FS version 2.0.0 in folder "E:/Software/Arduino/Arduino%20Sketches/libraries/FS"
Using library SPIFFS version 2.0.0 in folder "E:/Software/Arduino/Arduino%20Sketches/libraries/SPIFFS"
Using library WiFi version 2.0.0 in folder "E:/Software/Arduino/Arduino%20Sketches/libraries/WiFi"
Using library AsyncTCP version 1.1.4 in folder "E:/Software/Arduino/Arduino%20Sketches/libraries/AsyncTCP"
Using library ArduinoJson version 6.21.2 in folder "E:/Software/Arduino/Arduino%20Sketches/libraries/ArduinoJson"
Using library TaskScheduler version 3.7.0 in folder "E:/Software/Arduino/Arduino%20Sketches/libraries/TaskScheduler"
Using library Painless_Mesh version 1.5.0 in folder "E:/Software/Arduino/Arduino%20Sketches/libraries/Painless_Mesh"

Deep search is cached apart from the ino code. If you can also build vm again we can check that your cache is working properly.

We also need the painlessMesh.h and any other project files it references.

Thanks for the continued support. 
Error resolved. Thanks for the insightful advice. 
Let me inform the observations. 
There are worthy info to be noted and enhanced.

FS, SPIFFS & WiFi
architectures=esp32

Folders were removed and IDE restarted. Same error. 

The compiler output from Arduino IDE is attached for reference.


Earlier, with Deep search disabled, Visual micro mentioned missing libraries such as FS, SPIFFS, WiFi, TaskScheduler & ArduinoJson. So I declared them as headers. (Arduino didn't required the additional headers. I was not aware Arduino does deep search on every compilation) This worked for a long time. I recall version of esp32 core, painlessmesh & TaskScheduler were updated. Later the compile error started. 

Resolved method:
As you advised, deep search was enabled. Then the additional library headers were commented out. Only painlessmesh.h remained. It worked. 

With additional library headers and deep search enabled, same error was the result.
Would you please analyze what is causing this error?


Compile time difference:

Deep search enabled.
Compiled again with no change to the code

Program Painless_Mesh_Test size: 754792 bytes (used 38% of a 1966080 byte maximum) (3.91 secs)
Minimum Memory Usage: 42140 bytes (13% of a 327680 byte maximum)
-----------------------------------------------------------------------------


Deep search enabled.
Compiled again after changing a variable’s content. No change in library declaration

Program Painless_Mesh_Test size: 754792 bytes (used 38% of a 1966080 byte maximum) (19.99 secs)
Minimum Memory Usage: 42140 bytes (13% of a 327680 byte maximum)
-----------------------------------------------------------------------------

If there is no change in library declarations but only code changed, is it possible for visual micro to skip library deep search on compilations? This would save so many hours of development time.

Thanks a lot for helping with valuable inputs.