PrismLibrary/Prism · error · NavigationException

NavigationException.IConfirmNavigationReturnedFalse

NavigationException.IConfirmNavigationReturnedFalse

Error message

NavigationException.IConfirmNavigationReturnedFalse

What it means

GoBackInternalAsync calls MvvmHelpers.CanNavigateAsync, which invokes IConfirmNavigationRequest.CanNavigate/CanNavigateAsync on the current page or its ViewModel. When it returns false, Prism refuses the back navigation and throws NavigationException with code IConfirmNavigationReturnedFalse — navigation is aborted before the page is popped.

Solutions

Implement IConfirmNavigationRequest on the page/ViewModel so it returns true once edits are saved or the user confirms.
Save or discard pending changes before calling GoBackAsync so CanNavigate returns true.
Wrap GoBackAsync in try/catch for NavigationException and check the code NavigationException.IConfirmNavigationReturnedFalse to handle the refusal gracefully.
Use SendBackButtonPressed handling or a custom back-button handler to confirm with the user before navigating.

Example fix

// before
await _navigationService.GoBackAsync();
// after
try
{
    await _navigationService.GoBackAsync();
}
catch (NavigationException ex) when (ex.Code == NavigationException.IConfirmNavigationReturnedFalse)
{
    // prompt user to save changes or force-navigate
}

Defensive patterns

Strategy: try-catch

Validate before calling

bool canNavigate = (page as IConfirmNavigationRequest)?.CanNavigate(parameters) ?? true;
if (!canNavigate) { /* handle refusal before calling GoBackAsync */ }

Type guard

bool WillAllowBack(INavigationParameters p) =>
    !(_pageAccessor.Page is IConfirmNavigationRequest c) || c.CanNavigate(p);

Try / catch

try { await _navigationService.GoBackAsync(); }
catch (NavigationException ex) when (ex.Code == NavigationException.IConfirmNavigationReturnedFalse)
{ /* prompt user, save, or force navigation */ }

Prevention

Implement CanNavigate to return true by default and only block on real unsaved-state conditions
Save or commit state before programmatic back navigation
Always wrap programmatic GoBackAsync in NavigationException handling

When it happens

Trigger: Calling navigationService.GoBackAsync() (or RemoveAndGoBack) while the page being popped implements IConfirmNavigationRequest and its CanNavigate returns false — commonly a form with unsaved changes.

Common situations: Hardware/software back button triggering GoBackAsync on an editable page whose IConfirmNavigationRequest blocks exit; automated tests navigating back without satisfying the confirm condition; forgetting that CanNavigate returning false throws instead of silently no-op.

Understand the failure class

Background: "Invalid state transition" errors: "status must be X, actually Y", "already rejected/charging/uninstalled", "cannot ... while running" — what they mean when a library rejects your call — this error's family across 31 libraries.

Related errors

AI-assisted analysis of PrismLibrary/Prism@358118cd64 (2026-09-15). Data as JSON: /api/errors/a4a59f8276f38212. Report an issue: GitHub.

Appendix: source

Thrown at src/Maui/Prism.Maui/Navigation/PageNavigationService.cs:110

    }

    private async Task<INavigationResult> GoBackInternalAsync(INavigationParameters parameters)
    {
        Page page = null;
        try
        {
            parameters ??= new NavigationParameters();

            NavigationSource = PageNavigationSource.NavigationService;

            page = GetCurrentPage();

            parameters.GetNavigationParametersInternal().Add(KnownInternalParameters.NavigationMode, NavigationMode.Back);

            var canNavigate = await MvvmHelpers.CanNavigateAsync(page, parameters);
            if (!canNavigate)
            {
                throw new NavigationException(NavigationException.IConfirmNavigationReturnedFalse, page);
            }

            var dialogModal = IDialogContainer.DialogStack.LastOrDefault();
            if (dialogModal is not null)
            {
                if (dialogModal.Dismiss.CanExecute(null))
                    dialogModal.Dismiss.Execute(null);

                return Notify(NavigationRequestType.GoBack, parameters);
            }

            if (IsRoot(GetPageFromWindow(), page))
            {
                return SendAppToBackground(page);
            }

            bool useModalForDoPop = UseModalGoBack(page, parameters);
            Page previousPage = MvvmHelpers.GetOnNavigatedToTarget(page, Window?.Page, useModalForDoPop);

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