going from version 10 to 10.2 _TCHAR mapping causes trouble

Hello

I bought version 10.2 (Update 3) of C++ builder. My earlier version was 10. Most of the projects made with 10 do not link if "_TCHAR maps to" is set to wchar_t in debug mode. Even very simple ones, which do not have any "own"-code just different components. If I set "_TCHAR maps to" char then these old projects link ok. If I set "Build Configurations" to "release"-mode then I can use both wchar_t or char and both links ok.

Errors what I get are:

ilink32 error: unresolved external 'wWinMain' referenced from "c:\program files....\LIB\WIN32\RELEASE\COW32W.OBJ"

or

"First chance of exception at (hex address)... access violation.." and program stops on line 1123 in Vcl.Forms.hpp: " /* TCustomForm.Create */ inline __fastcall virtual TForm(System::Classes::TComponent* AOwner) : TCustomForm(AOwner) { }"

Does anyone know what is this  problem? Seems to be rather independent about the actual code made by me.

regards

Jarkko halme