dotnet/aspnetcore · error · InvalidOperationException

' {GetType().Name}' has not been initialized.

Error message

' {GetType().Name}' has not been initialized.

What it means

AssertInitialized throws InvalidOperationException when, after calling EnsureInitialized, _isInitialized is still false. This means the derived NavigationManager never called Initialize, so BaseUri/Uri are not set and any operation requiring them is unsafe.

Source

Thrown at src/Components/Components/src/NavigationManager.cs:611

    {
        AssertInitialized();

        if (_locationChangingHandlers.Remove(locationChangingHandler) && _locationChangingHandlers.Count == 0)
        {
            SetNavigationLockState(false);
        }
    }

    private void AssertInitialized()
    {
        if (!_isInitialized)
        {
            EnsureInitialized();
        }

        if (!_isInitialized)
        {
            throw new InvalidOperationException($"'{GetType().Name}' has not been initialized.");
        }
    }

    private static bool TryGetLengthOfBaseUriPrefix(Uri baseUri, string uri, out int length)
    {
        if (uri.StartsWith(baseUri.OriginalString, StringComparison.Ordinal))
        {
            // The absolute URI must be of the form "{baseUri}something" (where
            // baseUri ends with a slash), and from that we return "something"
            length = baseUri.OriginalString.Length;
            return true;
        }

        var pathEndIndex = uri.AsSpan().IndexOfAny('#', '?');
        var uriPathOnly = pathEndIndex < 0 ? uri : uri.AsSpan(0, pathEndIndex);
        if (baseUri.OriginalString.EndsWith('/') && uriPathOnly.Equals(baseUri.OriginalString.AsSpan(0, baseUri.OriginalString.Length - 1), StringComparison.Ordinal))
        {
            // Special case: for the base URI "/something/", if you're at

View on GitHub (pinned to 294cab2f9b)

Solutions

1. In your NavigationManager subclass, override EnsureInitialized (or the constructor) and call Initialize(baseUri, uri) once.
2. Ensure the host (renderer/server) initializes NavigationManager before rendering components that consume it.
3. In tests, call Initialize on the stub before exercising navigation code.

Example fix

// before
public class TestNavManager : NavigationManager { /* Initialize never called */ }

// after
public class TestNavManager : NavigationManager
{
    public TestNavManager() => Initialize("http://localhost/", "http://localhost/");
}

// Cannot read _isInitialized; ensure Initialize is called before use
public void EnsureReady()
{
    // Trigger AssertInitialized's lazy path or call Initialize once:
    try { _ = BaseUri; }
    catch (InvalidOperationException) { Initialize(_defaultBase, _defaultUri); }
}

try { var uri = navManager.Uri; }
catch (InvalidOperationException ex) when (ex.Message.Contains("not been initialized"))
{ logger.LogError(ex, "NavigationManager used before Initialize"); throw; }

When it happens

Trigger: Using a custom NavigationManager whose EnsureInitialized override does not call Initialize; accessing Uri/BaseUri/NavigateTo/LocationChanged before the host has initialized the manager; DI resolving NavigationManager too early in a non-Blazor host.

Common situations: Console/non-Blazor host wiring missing the Initialize call; component rendering attempted before the renderer set up NavigationManager; test harness that constructs NavigationManager but forgets Initialize.

Related errors

• ' {GetType().Name}' already initialized.
• Services cannot be accessed before the component is initiali
• PersistentComponentState already initialized.
• Renderer with ID '${rendererId}' is not listening for naviga
• No enhanced programmatic navigation handler has been attache

AI-assisted analysis of dotnet/aspnetcore@294cab2f9b (2026-08-06). Data as JSON: /api/errors/c576057688bd5444. Report an issue: GitHub.