CS0246: The type or namespace name 'ApplicationUserManager' could not be found

Question

My Visual Studio 2022 ASP.NET C# program was working fine.

After installing the latest updates for Visual Studio 2022 and Dependencies (Assemblies and Packages). I started to get the error in the title.

I have the Microsoft.AspNet.Identity.Core and Microsoft.AspNet.Identity.Owin packages are up to date in the project dependenceis. I cleaned the solution, deleted bin and obj folders, and rebuilt the solution. I have the following code in the *.aspx.cs files:
using Microsoft.AspNet.Identity;

using Microsoft.AspNet.Identity.Owin;

However, does not recognize ApplicationUserManager in the following code:

        var manager = Context.GetOwinContext().GetUserManager<ApplicationUserManager>();

How can I fix the error to build and run the solution again?

Answer 1

The error message "CS0246: The type or namespace name 'ApplicationUserManager' could not be found" indicates that the ApplicationUserManager class cannot be found. This could be due to a missing reference or a problem with the installation of the packages.

To resolve this issue, ensure that the Microsoft.AspNet.Identity.Core and Microsoft.AspNet.Identity.Owin packages are installed and up to date. You can check this by going to the NuGet Package Manager in Visual Studio and verifying that these packages are installed.

If the packages are installed and up to date, try cleaning and rebuilding the solution. If the issue persists, try deleting the bin and obj folders in the solution directory and rebuilding the solution.

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References:

• Account confirmation and password recovery with ASP.NET Identity (C#)
• Tutorial: Build a multitenant daemon that uses the Microsoft identity platform
• ASP.NET 4 Breaking Changes

Answer 2

Here are the exact message when I try to build the solution:

Error CS0246 The type or namespace name 'ApplicationSignInManager' could not be found (are you missing a using directive or an assembly reference?)

Error CS0246 The type or namespace name 'ApplicationUserManager' could not be found (are you missing a using directive or an assembly reference?)

How can I fix this error?

Thanks

Answer 3

Found the solution.

By hovering over the Function name and by clicking the IntelliSense message "Show potential fixes", Visual Studio 2022 added "using WebApp.App_Start;" to the code which fixed the problem.

Thank you!