I encourted a problem with FilePath Length ( > 260 chars) https://msdn.microsoft.com/en-us/library/windows/desktop/aa365247(v=vs.85).aspx   As a solution I try to use Windows "subst" command: And I make a wrraper UDF for this. Here is example how to use: #include <AutoItConstants.au3> #include <FileConstants.au3> #include <MsgBoxConstants.au3> #include "SubstWrapper.au3" _Subst_Example1() ;~ _Subst_Example2()