dotnet/wpf · error · ArgumentException

SR.AbsoluteUriNotAllowed

Error message

SR.AbsoluteUriNotAllowed

What it means

Application.LoadComponent(Object, Uri) only accepts relative Uris, because it resolves them against the application's pack base URI (PackAppBaseUri). An absolute Uri throws ArgumentException with SR.AbsoluteUriNotAllowed. The caller must pass a relative resource path such as "MyPage.xaml".

Solutions

  1. Pass a relative Uri: new Uri("MyPage.xaml", UriKind.Relative)
  2. Convert an existing absolute pack Uri to relative with BaseUriHelper or by stripping the pack base: BaseUriHelper.PackAppBaseUri.MakeRelativeUri(absUri)
  3. Use Navigation APIs (frame.Navigate) for absolute Uris instead of LoadComponent

Example fix

// before
var uri = new Uri("pack://application:,,,/Views/MyPage.xaml");
Application.LoadComponent(page, uri); // ArgumentException

// after
var uri = new Uri("Views/MyPage.xaml", UriKind.Relative);
Application.LoadComponent(page, uri);
Defensive patterns

Strategy: validation

Validate before calling

if (uri.IsAbsoluteUri)
    uri = BaseUriHelper.PackAppBaseUri.MakeRelativeUri(uri);
Application.LoadComponent(component, uri);

Type guard

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

Try / catch

try { Application.LoadComponent(component, uri); }
catch (ArgumentException) { uri = new Uri(Relativize(uri), UriKind.Relative); Application.LoadComponent(component, uri); }

Prevention

When it happens

Trigger: Calling LoadComponent(component, new Uri("pack://application:,,,/MyPage.xaml")) or any other absolute Uri (file://, http://, absolute pack://).

Common situations: Storing full pack URIs in configuration and passing them straight to LoadComponent; converting a NavigationWindow's absolute source Uri into a LoadComponent call; mixing up LoadComponent with NavigationService which does accept absolute Uris.

Understand the failure class

Background: "Invalid URL" errors: why new URL(), URI.parse, and reqwest::Url reject your string — missing scheme, whitespace, and bad path format — this error's family across 39 libraries.

Related errors

AI-assisted analysis of dotnet/wpf@81131a70a4 (2026-09-14). Data as JSON: /api/errors/699585f40d15a863. Report an issue: GitHub.

Appendix: source

Thrown at src/Microsoft.DotNet.Wpf/src/PresentationFramework/System/Windows/Application.cs:355

            }
        }

        /// <summary>
        /// Create logic tree from given resource Locator, and associate this
        /// tree with the given component.
        /// </summary>
        /// <param name="component">Root Element</param>
        /// <param name="resourceLocator">Resource Locator</param>
        public static void LoadComponent(Object component, Uri resourceLocator)
        {
            ArgumentNullException.ThrowIfNull(component);
            ArgumentNullException.ThrowIfNull(resourceLocator);

            if (resourceLocator.OriginalString == null)
                throw new ArgumentException(SR.Format(SR.ArgumentPropertyMustNotBeNull,"resourceLocator", "OriginalString"));

            if (resourceLocator.IsAbsoluteUri)
                throw new ArgumentException(SR.AbsoluteUriNotAllowed);

            // Passed a relative Uri here.
            // needs to resolve it to Pack://Application.
            //..\..\ in the relative Uri will get stripped when creating the new Uri and resolving to the
            //PackAppBaseUri, i.e. only relative Uri within the appbase are created here
            Uri currentUri = new Uri(BaseUriHelper.PackAppBaseUri, resourceLocator);

            //
            // Generate the ParserContext from packUri
            //
            ParserContext pc = new ParserContext
            {
                BaseUri = currentUri
            };

            bool bCloseStream = true;  // Whether or not to close the stream after LoadBaml is done.

            Stream stream = null;  // stream could be extracted from the manifest resource or cached in the

View on GitHub (pinned to 81131a70a4)