There was an error trying to log you in: ‘Invalid response Content-Type: text/html, from URL:’

I was implementing google authenticator feature on my Blazor web assembly POC demo. I was getting this exception

There was an error trying to log you in: ‘Invalid response Content-Type: text/html, from URL:’

My program.cs file was like

My appsettings.json file was like this

Workaround fix for this

>> change any name expect Local. You can give google or any other name. I hope it will help other developer.


CRUD Operation in Core Blazor

In this Demo project, I have created the CRUD(Create,Read,Update,Delete) operation using core blazor. It has very simple Emp table with EmpId,Name,City,Country and Gender field.

It has the following features

1. Entity Framework using Code Fist for Insert,update,Read and delete functionality
2. FluentValidator for validation in Blazor
3. Implementation of Log functionality using log4Net in Blazor
4. Custom paging on Grid

Please download the code from this URL

State Management in Core Blazor Server

State Management is the process of maintaining state in one page to other page or entire application page. In each framework there would be separate approach to achieve statement.

Blazor Server is a stateful app framework. Most of the time, the app maintains an ongoing connection to the server.

There are so many approach to implement statement in Blazor Server. But I will show you one of the best and easy approach using AppState pattern.

In this demo we create CurrentCount as global variable to access in other page of blazor.

Step 1: Create the default blazor server demo project and go project folder >> Create CounterState.cs file, Create CurrentCount properties like this.

Step 2: Register in Startup file of blazor like this

Step 3: Go to the index.razor component file and inject the Counter Component like this

Step 4: Go to the Couter.razor component file write the code like this

@page "/counter"
@inject CounterState State;


<p>Current count: @State.CurrentCount</p>

<button class="btn btn-primary" @onclick="IncrementCount">Click me</button>

@code {

    private void IncrementCount()

Step 5: Run the application and click on counter button and verify it on Home page.


In this small demo we saw that how to maintain the state in two Blazor page using one of the simplest approach.

Cascading Values & Cascading Parameters in core Blazor

Today i was working on one blazor POC project, there i got a requirement to pass some value to all the child components which one i was using on the parent component.

Then i found one of the best approach to pass in all the child component using Cascading Values & Cascading Parameters

Let see this concept one small example.

Step 1: Create the parent component like this

@page "/home"

<CascadingValue Value="@FirstFruit" IsFixed="true" Name="FirstFruit">

@code {
    string FirstFruit { get; set; } = "Apple";

In the above code, i m passing FirstFruit property to all the child component, There could be multiple child component. For simplicity i have taken only one.

IsFixed=”true” means Blazor will not monitor it for changes. It is good practice to improve the performance when there will be multiple child component.

Step 2: Create the Fruit Component like this.

<h5>Demo for Cascading Value and Cascading Parameter</h5><br />

<p>The fruit Name is: @Name </p>

@code {
    [CascadingParameter(Name = "FirstFruit")] 
    string Name { get; set; }

In the above code CascadingParameter means which field will receive the Cascading Value.
(Name = “FirstFruit”): Means which field we are going to bind from parent component.


In this sample we saw that how pass the value from parent component to multiple child component with a very minimal coding.

QueryString in Core Blazor

Querystring is generally used for passing data from one page to other page. But in Core Blazor very straight forward to read the query string.

Step 1: Create the page from where you will pass the query string data. I have created in index page like this.

@page "/"

<h3>Query string Demo</h3>
<a href="/querystringpage?a=2&b=4">Click Here</a> <br />

<br />
<form action="querystringpage">
    First Num1 : <input name="a" /> 
    Second Num2 : <input name="b" />
    <input type="submit" />

Step 2: Create the page where you are going to read the query string data.

@page "/querystringpage"
@inject NavigationManager nav
@using Microsoft.AspNetCore.WebUtilities

URI: @uri;
<br />

Num1 :@a <br />
Num2 :@b <br />
Sum of Two Num: <b>@c</b>

@code {
    System.Uri uri;
    int a;
    int b;
    int c;
    protected override void OnInitialized()
        uri = nav.ToAbsoluteUri(nav.Uri);
        if (QueryHelpers.ParseQuery(uri.Query).TryGetValue("a", out var aVal))
            a = int.Parse(aVal);
        if (QueryHelpers.ParseQuery(uri.Query).TryGetValue("b", out var bVal))
            b = int.Parse(bVal);
        c = a + b;


In the above code, we saw that we are using Microsoft.AspNetCore.WebUtilities namespace, which has the helper method i.e. QueryHelpers to extract the query string value. We have also injected the NavigationManager the url path of page.


In this small demo, we saw that how QueryHelpers method of Microsoft.AspNetCore.WebUtilities namespace simplified our code to read the query string in core Blazor.