ERROR_ENVVAR_NOT_FOUND

SetLastError(0);
    RPC_CSTR rpcGuidStr_L = nullptr;
    GUID* PgGuid_L = nullptr;
    std::string sGuid_L = "";  
    PgGuid_L = new GUID;   
    CoCreateGuid(PgGuid_L);
    if (GetLastError() != 0){std::cout << GetLastError() << "001\n"; _getch(); exit(1);}
    UuidToStringA(PgGuid_L, &rpcGuidStr_L);
    if (GetLastError() != 0){std::cout << GetLastError() << "002\n"; _getch(); exit(1);}
    sGuid_L = (char*)rpcGuidStr_L;
    RpcStringFreeA(&rpcGuidStr_L);
    delete PgGuid_L;
    std::cout << sGuid_L;