You're using a relative path - are you sure it is in current working directory when you call open?
"Access is denied" - you're trying to open in write mode - are you sure the file is in a writeable location and is writeable?
If I using qt mingw there is no problem to create or open any file but with UWP it impossible to create file at any location .
also I try to open UART that is simple with mingw but I didn't success
I didn't success to use any file IO system call when I use the UWP framework.
do you have any example for UWP QT application that access file system or Serial Port ?