dotnet/maui · error · ArgumentException

uri

Error message

uri

What it means

Platform.cs throws ArgumentException("uri") on the else branch when the supplied uri is not a recognized file-style Uri at all (i.e. it is null or not usable as a local file). This is the fallback for unrecognized inputs that did not match the file-path resolution logic.

Source

Thrown at src/Compatibility/Core/src/iOS/Platform.cs:663

				if (uri.LocalPath.StartsWith("/local"))
				{
					var libraryPath = NSFileManager.DefaultManager.GetUrls(NSSearchPathDirectory.LibraryDirectory, NSSearchPathDomain.User)[0].Path;
					filePath = IOPath.Combine(libraryPath, uri.LocalPath.Substring(7));
				}
				else if (uri.LocalPath.StartsWith("/temp"))
				{
					filePath = IOPath.Combine(IOPath.GetTempPath(), uri.LocalPath.Substring(6));
				}
				else
				{
					throw new ArgumentException("Invalid Uri", "Source");
				}

				return filePath;
			}
			else
			{
				throw new ArgumentException("uri");
			}
		}

		internal void SubscribeToAlertsAndActionSheets()
		{
			var busyCount = 0;
			MessagingCenter.Subscribe(this, Page.BusySetSignalName, (Page sender, bool enabled) =>
			{
				if (!PageIsChildOfPlatform(sender))
					return;
				busyCount = Math.Max(0, enabled ? busyCount + 1 : busyCount - 1);
#pragma warning disable CA1416, CA1422  // TODO: 'UIApplication.NetworkActivityIndicatorVisible' is unsupported on: 'ios' 13.0 and later
				UIApplication.SharedApplication.NetworkActivityIndicatorVisible = busyCount > 0;
#pragma warning restore CA1416, CA1422
			});

			MessagingCenter.Subscribe(this, Page.AlertSignalName, (Page sender, AlertArguments arguments) =>
			{

View on GitHub (pinned to f377ff1c5e)

Solutions

1. Validate the uri is non-null and absolute before passing.
2. For remote images use UriImageSource with an http(s) Uri; for local files use the correct /local or /temp prefix.
3. Guard the binding path so a null/empty Uri does not reach the platform resolver.

Example fix

// before
var path = Platform.ResolveUri(uri);
// after
if (uri == null || !uri.IsAbsoluteUri)
    throw new ArgumentException("A valid absolute file Uri is required.", nameof(uri));
var path = Platform.ResolveUri(uri);

if (uri == null || !uri.IsAbsoluteUri)
    throw new ArgumentException("A valid absolute Uri is required.", nameof(uri));

static bool IsValidAbsoluteUri(Uri u) => u != null && u.IsAbsoluteUri;

When it happens

Trigger: Passing a null or unsupported uri value to the platform's Uri resolver; a Uri that is not absolute and not a recognized scheme.

Common situations: Setting ImageSource to a null Uri; passing a relative Uri; feeding an http Uri where a file Uri is required by the local-file resolution path; binding source set before Uri assignment.

Related errors

• Invalid Uri
• indexPath
• group
• indexPath
• view

AI-assisted analysis of dotnet/maui@f377ff1c5e (2026-08-13). Data as JSON: /api/errors/1bac3db43e60366b. Report an issue: GitHub.