PrismLibrary/Prism · error · NavigationException

NavigationException.NoPageIsRegistered

NavigationException.NoPageIsRegistered

Error message

NavigationException.NoPageIsRegistered

What it means

The parameterless-segment TabbedSegmentBuilder constructor queries the registry for TabbedPage registrations and throws NavigationException(NoPageIsRegistered) when none exist. Prism cannot pick a default TabbedPage segment name without a registration.

Solutions

1. Register TabbedPage: `registry.RegisterForNavigation<TabbedPage>(nameof(TabbedPage));` before creating tabs.
2. Use the TabbedSegmentBuilder(builder, segmentName) overload only after ensuring a matching named registration exists.
3. Confirm the registration module/extension that adds TabbedPage actually runs at app startup.

Example fix

// before
builder.AddNavigationPage(b => b.AddTabbedSegment()); // throws: no TabbedPage registered
// after
registry.RegisterForNavigation<TabbedPage>(nameof(TabbedPage));
builder.AddNavigationPage(b => b.AddTabbedSegment());

if (!((IRegistryAware)builder).Registry.ViewsOfType(typeof(TabbedPage)).Any())
    throw new InvalidOperationException("Register TabbedPage before creating a tabbed segment");

null

try { builder.AddNavigationPage(b => b.AddTabbedSegment()); }
catch (NavigationException ex) when (ex.Code == NavigationException.NoPageIsRegistered)
{
    // register TabbedPage at startup or use a different segment type
}

When it happens

Trigger: Calling `new TabbedSegmentBuilder(navigationBuilder)` (or an API that constructs it, like a builder AddTabbedSegment overload) when the IViewRegistry has no registration for typeof(TabbedPage).

Common situations: Apps using TabbedPage without registering it in the Prism registry; MAUI Shell apps migrated to Prism where TabbedPage registration was skipped; missing `RegisterForNavigation<TabbedPage>` call at startup.

Understand the failure class

Background: "Not found" and "does not exist" errors: why "Task not found", "No such folder", and "Can't find" fire when a lookup comes back empty — this error's family across 14 libraries.

Related errors

• NavigationException.NoPageIsRegistered
• The builder does not implement IRegistryAware
• configureSegment
• No Registration found to select tab
• The page type ' ' is not supported.

AI-assisted analysis of PrismLibrary/Prism@358118cd64 (2026-09-15). Data as JSON: /api/errors/658218cd5bb3ef20. Report an issue: GitHub.

Appendix: source

Thrown at src/Maui/Prism.Maui/Navigation/Builder/TabbedSegmentBuilder.cs:21

namespace Prism.Navigation.Builder;

internal class TabbedSegmentBuilder : ITabbedSegmentBuilder, IConfigurableSegmentName, IUriSegment, IRegistryAware
{
    private INavigationParameters _parameters { get; }
    private INavigationBuilder _builder { get; }

    public TabbedSegmentBuilder(INavigationBuilder builder)
    {
        _builder = builder;
        _parameters = new NavigationParameters();

        if (builder is not IRegistryAware registryAware)
            throw new Exception("The builder does not implement IRegistryAware");

        var registrations = registryAware.Registry.ViewsOfType(typeof(TabbedPage));
        if (!registrations.Any())
            throw new NavigationException(NavigationException.NoPageIsRegistered, nameof(TabbedPage));

        var registration = registrations.Last();
        SegmentName = registration.Name;
    }

    public TabbedSegmentBuilder(INavigationBuilder builder, string segmentName)
    {
        _builder = builder;
        _parameters = new NavigationParameters();

        if (builder is not IRegistryAware registryAware)
            throw new Exception("The builder does not implement IRegistryAware");

        var registration = registryAware.Registry.ViewsOfType(typeof(TabbedPage)).FirstOrDefault(x => x.Name == segmentName);
        if (registration == null)
            throw new NavigationException(NavigationException.NoPageIsRegistered, nameof(TabbedPage));

        SegmentName = registration.Name;

View on GitHub (pinned to 358118cd64)