I really think that when Installer sees that it does not have write access to the last installation path [C:\Program Files (x86)\WinSCP]
then it has to propose the path:%APPDATA%
which is equal to:{HOMEDRIVE}:\Users\{username}\AppData\Roaming
It does that. But for new installations only. For upgrades, it's difficult to guess, what the user actually wants. Perhaps the installer should ask.
I do understand you, Martin.
1. Logically the Installer sees that the folder
C:\Program Files (x86)\WinSCP\
exists.
2. So Installer wants ti Upgrade in this case.
3. But then Installer checks that folder for Write access and fails.
At such situation (and this is my situation) I really thing that Installer has to propose to make a new installation and may be to move setting from old directory to a new one.
Also the steps 1.2.3. can be hidden for user so he just sees a note that only New installation to New folder can be made (with proposal to move setting if the *.ini file is kept in old folder).