And according to Qt's QStandardPaths docs, AppLocalData value defined as:
Returns the local settings path on the Windows operating system. On all other platforms, it returns the same value as AppDataLocation.
And here are the templates for the AppLocalDataLocation on Windows:
"C:/Users/<USER>/AppData/Local/<APPNAME>",
"C:/ProgramData/<APPNAME>",
"<APPDIR>",
"<APPDIR>/data",
"<APPDIR>/data/<APPNAME>"
And the Windows specific code and calls that determine these can be found here:
https://github.com/qt/qtbase/blob/20...dpaths_win.cpp
So check what environment vars you have set? Also check permissions to verify that the location / path is actually writeable by the user.
This code literally has not changed in years in Sigil so it is most likely an issue on your specific machine.