How to handle Controlled Folder Access restrictions in SaveFileDialog?

CFA
1

I’m working on an app that needs to write files to user-selected folders. The problem is when Controlled Folder Access (CFA) is on. If a user tries to save in a CFA-protected folder, like Documents, it’s blocked. The error message is confusing, saying ‘file not found’ and showing a system tray notification about CFA blocking the app.

I can check for CFA at startup and give a clear message. But I can’t do this in SaveFileDialog. After the ‘file not found’ error, the dialog closes without info on where the user tried to save.

How can I give a helpful message when SaveFileDialog hits a CFA folder? I don’t want to force users to allow the app by default, as not everyone uses CFA. Any ideas on how to handle this without confusing users?

2

Hey there! This is a tricky situation, isn’t it? :thinking: I’ve been wondering about something similar myself.

Have you considered trying to guide users towards safer locations by default? Maybe you could set the initial directory of the SaveFileDialog to a folder that’s less likely to be protected by CFA, like the user’s Downloads folder?

Something like:

saveFileDialog.InitialDirectory = Environment.GetFolderPath(Environment.SpecialFolder.UserProfile) + "\Downloads";

This way, you’re subtly steering users away from potential CFA issues without explicitly restricting their choices. Plus, it might save them a few clicks!

I’m curious though - have you noticed any patterns in terms of which folders tend to cause problems most often? It might be helpful to compile a list of ‘high-risk’ locations to watch out for.

Oh, and here’s a wild thought - what if you implemented a simple ‘test save’ feature that users could run voluntarily? It could check a bunch of common locations and report back on which ones are safe to use. Might be overkill, but could be a fun addition for power users!

What do you think? Have you tried anything like this already?

3

yo, that’s a tough one. what if u try catching the specific exception when saving? like, wrap ur save code in a try-catch and look for that ‘UnauthorizedAccessException’. then u could pop up a message saying ‘hey, looks like CFA’s blockin this. try a different spot or add the app to ur allowed list’. might help users figure out whats goin on

4

I’ve faced a similar issue with Controlled Folder Access in one of my projects. Unfortunately, there’s no direct way to detect CFA restrictions within SaveFileDialog. However, here’s a workaround I’ve found effective:

After the user selects a location in SaveFileDialog, but before actually writing the file, perform a test write to that location using a temporary file. If this fails due to CFA, you can catch the specific exception and provide a clear message about the restriction.

Something like:

try {
    string tempFile = Path.Combine(selectedPath, "test.tmp");
    File.WriteAllText(tempFile, "test");
    File.Delete(tempFile);
} catch (UnauthorizedAccessException) {
    MessageBox.Show("Controlled Folder Access is preventing the save. Please choose a different location or add this app to the allowed list in Windows Security settings.");
    return;
}

This approach allows you to give users specific guidance without relying on the limited error handling in SaveFileDialog itself.