Issue to lcoate the file regarding FileSystem.CacheDirectory

FileSystem.CacheDirectory in .NET MAUI returns a platform-specific temporary folder path that is private to the app. It is not mapped directly under

C:\Users\huang.scott\AppData\Local\Packages

in a way that is intended for manual browsing.

Key points about FileSystem.CacheDirectory:

• It is a temporary data location for the app.
• It is usually not visible to the user.
• It is not backed up.
• It may be cleared by the operating system at any time.

Because of this, the exact on-disk path is implementation- and platform-dependent and is not guaranteed to be stable or discoverable through the normal Packages folder layout. Code should treat FileSystem.CacheDirectory as an opaque path and not rely on finding or manipulating those files manually in the Windows file system.

If the physical path is needed for diagnostics, log the value of FileSystem.CacheDirectory at runtime from within the app (for example, to the debug output) and use that logged path for inspection, understanding that it is temporary and may be deleted by the OS.

References:

• FileSystem.CacheDirectory Property
• IFileSystem.CacheDirectory Property

This exact issue was addressed in your previous thread: [Link].

You are still ignoring the fact that you defined the localPath yourself. The file is exactly where you told the program to put it. However, because you are using FileSystem.CacheDirectory, you have placed the file in a private, sandboxed directory. On mobile devices, this location is hidden from the user and will never appear in a File Explorer.

Can you describe the application you are building and tells us how it is designed to function? For example, is this a desktop application running on Windows, a Mobile app...? Have you at least verified that your REST call to fetch the file works as expected? https://learn.microsoft.com/en-us/dotnet/api/microsoft.maui.storage.filesystem.cachedirectory?view=net-maui-10.0

https://learn.microsoft.com/en-us/dotnet/maui/platform-integration/storage/file-system-helpers?view=net-maui-10.0&tabs=windows

Hi @Scott Huang ,

Thanks for reaching out.

For that code, the file is saved under the value returned by FileSystem.CacheDirectory, with fileName added to the end of it.

On Windows, if this is a packaged .NET MAUI app, FileSystem.CacheDirectory maps to the app's local cache folder. Under C:\Users\huang.scott\AppData\Local\Packages, you need to open the folder for your app package first, then look in LocalCache.

The path is usually like this:

C:\Users\huang.scott\AppData\Local\Packages\<PackageFamilyName>\LocalCache\<fileName>

The <PackageFamilyName> folder is generated by Windows, so it may not have exactly the same name as your project. If you are not sure which folder is the correct one, the safest way is to print the full path from the app:

string localPath = Path.Combine(FileSystem.CacheDirectory, fileName);
System.Diagnostics.Debug.WriteLine($"localPath: {localPath}");

Run the app in Visual Studio and check the Output window. The printed localPath value is the exact location where the file is being created.

You can also confirm that the file was actually written before calling the share API:

await stream.CopyToAsync(fileStream);

if (File.Exists(localPath))
{
    System.Diagnostics.Debug.WriteLine($"File created: {localPath}");
}

If the file is not there, then the first thing to check is whether the download stream was copied successfully and whether fileName has the expected value.

One more note: FileSystem.CacheDirectory is meant for temporary/cache files. It is private to the app and may be cleared by the operating system. If the file needs to be kept longer, use FileSystem.AppDataDirectory instead. If the file is only created so it can be shared immediately, using CacheDirectory is fine.

Hope this helps! If my answer was helpful, I would greatly appreciate it if you could follow the instructions here so others with the same problem can benefit as well.