How does Windows determine which folder AppData local data goes in? - windows

Question

I know that local application data is stored in a set location on disk for my application:
c:\Users\jonathan\AppData\Local\MyCompany\MyApp_In_Question_Url_fhjsu6dhsj673dkncsdhjfdf
This contains several sub-folders containing the application settings (user.config), which generally take the form "6.1.5944.23465".
We do a straight file copy over the install location, and running the new executable from the shortcut on the desktop for the first time usually creates a new sub-folder of the same form (i.e. 6.1.5966.34567), which requires us to call Settings.Upgrade
So far, so good (although this probably isn't good practice).
I have just recently upgraded the application from .NET 3.5 to .NET 4.6.2, and on some machines it creates a new folder entirely:
c:\Users\jonathan\AppData\Local\MyCompany\MyApp_In_Question_Url_aaabf35hhsjd4hkwn83kfcm
And a new sub-folder of the form 6.1.5977.10245.
This is an issue because the shortcut on the desktop no longer works, and the settings cannot be upgraded, and require re-entry by the end-user (who doesn't always know them).
Most machines (all the test and UAT ones) do not exhibit this behaviour.
My question is this:
What is the mechanism for deciding that an executable's settings should be stored in an entirely new location, and not a sub-folder?
As a corollary of this:
Can I set this so that it's definitely the same product, and the settings can continue to be upgraded?

Answer 1

I realised that sometimes the flow of code creates the first setting from a dll, and sometimes from the main executable, and I do some custom setting of My.Settings (in one of the VB chunks) which is a little messy.
In case you wondered: To recover the settings, I had to search through all the LocalApplicationData looking for my app's previous settings.
Private Shared Function FindFromPreviousSettings() As MigratableSettings
' Find the App_Data folder, and look to see if there are any other
' config settings which are valid, authenticated, etc.
Dim likelyConfigPath = New DirectoryInfo(
Path.Combine(
Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData),
"My_Software_Company"
)
)
Dim allValidConfigs = SearchMyDirectory(likelyConfigPath, "user.config")
Dim ver As Func(Of FileInfo, Version)
ver = Function(fi)
Try
'Find out the version of this file. Bigger is better.
Return New Version(fi.Directory.Name)
Catch ex As Exception
Return New Version()
End Try
End Function
Dim latestValidFile = allValidConfigs.OrderByDescending(ver).FirstOrDefault()
Dim latestValidSettings = ReadSettingsFromConfigFile(latestValidFile)
Return latestValidSettings
End Function