unoplatform/uno · error · NotSupportedException

IStorageFile is not supported

Error message

IStorageFile is not supported

What it means

NotSupportedException thrown by MediaPlayerExtension.SetFileSource on WebAssembly. The WASM media player is HTML <video>-based and only supports Uri sources; file-backed (IStorageFile) sources are explicitly unsupported. Calling SetFileSource on the WASM target always throws.

Source

Thrown at src/AddIns/Uno.UI.MediaPlayer.WebAssembly/MediaPlayerExtension.cs:464

			{
				if (this.Log().IsEnabled(LogLevel.Debug))
				{
					this.Log().Debug($"MediaPlayerExtension.Play(): Player was not prepared");
				}
			}
		}
		catch (global::System.Exception ex)
		{
			if (this.Log().IsEnabled(LogLevel.Debug))
			{
				this.Log().Debug($"MediaPlayerExtension.Play(): Failed {ex}");
			}
			OnMediaFailed(ex);
		}
	}

	public void SetFileSource(IStorageFile file)
		=> throw new NotSupportedException($"IStorageFile is not supported");

	public void SetMediaSource(IMediaSource source)
		=> throw new NotSupportedException($"IMediaSource is not supported");

	public void SetStreamSource(IRandomAccessStream stream)
		=> throw new NotSupportedException($"IRandomAccessStream is not supported");

	public void SetSurfaceSize(Size size)
		=> throw new NotSupportedException($"SetSurfaceSize is not supported");

	public void SetUriSource(Uri uri)
	{
		if (this.Log().IsEnabled(LogLevel.Debug))
		{
			this.Log().Debug($"MediaPlayerExtension.SetUriSource({uri})");
		}

		if (_player is not null)

View on GitHub (pinned to 0418340488)

Solutions

1. On WASM, obtain a playable URI (blob URL or remote URL) and use SetUriSource instead of SetFileSource.
2. Branch platform-specific source-setting: use StorageFile on desktop, Uri on WASM.
3. If you have a local file, create an object URL in JS and pass it as a Uri.
4. Avoid calling SetFileSource entirely on WASM; guard with OperatingSystem.IsBrowser()/platform checks.

Example fix

// before — shared code calls SetFileSource
extension.SetFileSource(pickedFile);

// after — branch by platform
#if __WASM__
    extension.SetUriSource(new Uri(blobUrl));
#else
    extension.SetFileSource(pickedFile);
#endif

// Do not call SetFileSource on WASM
if (!OperatingSystem.IsBrowser())
    extension.SetFileSource(file);
else
    throw new PlatformNotSupportedException("Use SetUriSource on WASM");

bool SupportsFileSource() => !OperatingSystem.IsBrowser();

try { extension.SetFileSource(file); }
catch (NotSupportedException ex) when (ex.Message.Contains("IStorageFile"))
{ Log.Error("File sources unsupported on WASM — use a Uri"); }

When it happens

Trigger: Code path that calls SetFileSource(IStorageFile) on the WASM media extension — e.g. a shared cross-platform codebase that, on WASM, attempts to play from a StorageFile obtained via a file picker.

Common situations: Cross-platform media code that uses StorageFile/FileOpenPicker to pick a local file and feeds it to the media player; porting desktop behavior to WASM where only URIs are playable due to browser sandbox restrictions.

Related errors

• IMediaSource is not supported
• IRandomAccessStream is not supported
• SetSurfaceSize is not supported
• MediaPlayerPresenterExtension must be initialized with a Med
• Playlist Items could not be set

AI-assisted analysis of unoplatform/uno@0418340488 (2026-08-13). Data as JSON: /api/errors/26f6f81cb6a3e334. Report an issue: GitHub.