Azure ASP.NET Core POST 400 bad request Blazor Webassembly


I have been trying to deploy my core hosted blazor webassembly app on Azure App Service, however, I am having trouble getting the api to work. When I try and save a user's data in the database, I get a 400 bad request error. It works fine on localhost. I looked around and found advice that suggested that I use the Log Stream in Azure to get a more detailed error message, and here it is although I'm not sure the details really help.

2020-06-22 22:24:54 MYPROJECT POST /api/Register/Post X-ARR-LOG-ID=ef27263e-dead-417a-b136-89a217a6f931 443 - MYIP Mozilla/5.0+(Windows+NT+10.0;+Win64;+x64)+AppleWebKit/537.36+(KHTML,+like+Gecko)+Chrome/83.0.4103.97+Safari/537.36 ARRAffinity=7f74b113b9ae575a087ae1fa07a63858e6e34f27224b7aa1a957b06074e65ffd

Here is the relevant application code:

//Register.razor in client project
@code {
    private RegisterModel Model = new RegisterModel();
    private bool ShowErrors;

    private List<string> Errors = new List<string>();
    private async Task HandleValidSubmit()
        ShowErrors = false;
        if (Model.Password.Length >= 6 && Model.Password == Model.ConfirmPassword)
            await HttpClient.PostAsJsonAsync<RegisterModel>("api/Register/Post", Model);
            if (Model.Password.Length > 100 || Model.Password.Length < 6)
                Errors.Add("Password must be between 6 and 100 characters in length.");
            if (Model.Password != Model.ConfirmPassword)
                Errors.Add("Passwords do not match.");
            ShowErrors = true;

//RegisterController.cs in server project
    public class RegisterController : Controller
        private UserContext UserContext { get; set; }
        private IHasher Hasher = new Pbkdf2Hasher();
        public RegisterController (UserContext userContext)
            UserContext = userContext;

        public async Task Post([FromBody]RegisterModel model)
            var user = new UserModel
                Email = model.Email,
                Password = Hasher.Hash(model.Password)
            await UserContext.AddAsync(user);
            await UserContext.SaveChangesAsync();

//Startup.cs in Server project
            public void ConfigureServices(IServiceCollection services)
                services.AddDbContext<UserContext>(options =>
                    sqlServerOptionsAction: sqlOptions =>

On publishing the project, I configured an Azure SQL Database for 'users', checked the checkboxes to use the UsersConnection string at runtime, and apply the UserContext Entity Framework Migration on publish.

I am using visual studio 2019, and the target framework is netcoreapp3.1. I'd appreciate any guidance. Thanks!


After looking at the detailed logs, apparently the database isn't even being made?

INSERT INTO [Users] ([Email], [Password])
VALUES (@p0, @p1);
2020-06-22 22:19:47.208 +00:00 [Error] Microsoft.EntityFrameworkCore.Update: An exception occurred in the database while saving changes for context type 'BlazorTodos.Server.Data.UserContext'.
Microsoft.EntityFrameworkCore.DbUpdateException: An error occurred while updating the entries. See the inner exception for details.
 ---> Microsoft.Data.SqlClient.SqlException (0x80131904): Invalid object name 'Users'.
asked on Stack Overflow Jun 22, 2020 by amdorsey12 • edited Jun 24, 2020 by amdorsey12

1 Answer


Thanks for all the suggestions, Jason. Helped me head in the right direction.

The problem was quite silly. Apparently the Database and Entity Framework settings had automatically come up with the same string for both my "Users" and "Todos" databases:

Data,1433;Initial Catalog=todos;User Id=<myid>@myserver;Password=<my-password>

But I hadn't noticed that it was the same string. I just had to change Initial Catalog to users and re check the "use this connection string at runtime" and "apply this migration on publish" boxes again with the edited string. That solved the issue.

answered on Stack Overflow Jun 25, 2020 by amdorsey12

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