Android Tutorial [B4X] Tip - ROBOCOPY error related to shared files folder

You download a project from the forum and when you run it, you get an error message similar to:

B4A Version: 10.2
Java Version: 8
Parsing code.    (0.11s)
Building folders structure.    (0.02s)
Running custom action.    Error
   ROBOCOPY     ::     Robust File Copy for Windows                             
  Started : Tuesday, November 10, 2020 8:05:40 AM
   Source : C:\Users\H\DOWNLO~1\projects\Shared Files\
     Dest : C:\Users\H\DOWNLO~1\projects\B4A\Files\
    Files : *.*
  Options : *.* /DCOPY:DA /COPY:DAT /R:1000000 /W:30
2020/11/10 08:05:40 ERROR 2 (0x00000002) Accessing Source Directory C:\Users\H\DOWNLO~1\projects\Shared Files\
The system cannot find the file specified.

Fix - Go to the top of B4XMainPage and delete this line:
#CustomBuildAction: folders ready, %WINDIR%\System32\Robocopy.exe,"..\..\Shared Files" "..\Files"

Why it happens?

It happens with B4XPages projects, when the developer uses File - Export as zip to create the zip file instead of clicking on:
'Ctrl + click to export as zip: ide://run?File=%B4X%\Zipper.jar&
The Zipper tool is more sophisticated and it preserves the B4XPages project structure.