Found markup element with unexpected name 'Cascading AuthenticationState'

Question

I am getting this error on my App.razor:

Found markup element with unexpected name 'CascadingAuthenticationState'. If this is intended to be a component, add a @using directive for it namespace

This is the code I am using

<CascadingAuthenticationState>
    <Router AppAssembly="@typeof(Program).Assembly">
        <Found Context="routeData">
            <RouteView RouteData="@routeData" DefaultLayout="@typeof(MainLayout)" />
        </Found>
        <NotFound>
            <LayoutView Layout="@typeof(MainLayout)">
                <p>Sorry, there's nothing at this address.</p>
            </LayoutView>
        </NotFound>
    </Router>
</CascadingAuthenticationState>

I am using Visual Studio 2019 preview and I can run the application but, why do I have the red line in the Cascading....?

That code by itself is OK, you are probaly using the wrong packages. Make sure you are up to date to the 3.0 released version. For an existing project, follow the update guidelines. — Henk Holterman, Oct 11 '19 at 08:25
@HenkHolterman Could you please point out what package to install for that error? — Ibanez1408, Oct 11 '19 at 08:58
But I now see the client-side tag. The App.razor you posted is for server-side. — Henk Holterman, Oct 11 '19 at 09:02
but it is in the client side. Ever since last update, I couldn't run this anymore. on my last work, before this last update, i was able to make this run without issues. — Ibanez1408, Oct 11 '19 at 09:07
post the contents of your csproj. More specifically, the `ItemGroup` containing all the `` — Tewr, Oct 11 '19 at 11:56

score 10 · Answer 1 · answered Oct 21 '19 at 16:19

10

For me adding both references to _Imports.razor worked to solve same issue:

@using Microsoft.AspNetCore.Authorization
@using Microsoft.AspNetCore.Components.Authorization

answered Oct 21 '19 at 16:19

Konstantin Salavatov

3,925
2
23
24

Don't forget to also install the correct NuGet pages for this to work. – Justin Feb 16 '21 at 13:06

score 10 · Answer 2 · answered Sep 11 '20 at 13:58

10

Warning! The .vs folder contains all the data that VS gathered about the projects in your solution, the opened files, debug. You will lose all that!

Close Visual Studios and delete the .vs hidden folder in the root of your solution.

Start up your project and the error's will be gone.

answered Sep 11 '20 at 13:58

Katey

141
2
6

1

This one worked for me. I was using LTS versions for packages so updates SHOULD not be needed! – David Jones Oct 15 '20 at 11:53

score 2 · Answer 3 · answered Jan 05 '20 at 21:34

2

Right Click Project
Manage Nuget Packages
Select "Microsoft.AspNetCore.Blazor" which you have already installed.
Update with Latest stable version then...
Update Latest preview again.

answered Jan 05 '20 at 21:34

ahmetsse

61
4

I've had to do this twice now and twice this has helped me because it reminded me to check for NuGet updates, which fixed the problem. – Tod Sep 23 '20 at 13:24

score 0 · Answer 4 · answered Nov 03 '20 at 20:17

0

Looks like it's an IntelliSense issue of the VisualStudio, see: https://developercommunity.visualstudio.com/content/problem/770539/visual-studio-lost-intellisense-for-blazor-compone.html

answered Nov 03 '20 at 20:17

Alex

999
1
10
11

Found markup element with unexpected name 'Cascading AuthenticationState'

4 Answers4

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