Why does Scaffolding Identity for .NET Core 3.1 and .NET 5 in Visual Studio 2019 16.9.5 fail?

Question

I'm trying to generate Identity Account\Login and Account\Register pages in a new project. I've tried both .NET Core 3.1 and .NET 5; in both cases, even when it's a new project, I receive the following error message:

An incredibly helpful error message, as you can tell. Does anybody know what can cause this with .NET Core 3.1 or .NET 5 projects and how to fix it? I've got VS2019 v16.9.5 installed, Microsoft's IdentityServer v.5.0.6, EntityFrameworkCore v.5.0.6, Identity.UI v5.0.6, and CodeGeneration.Design v.5.0.2 all installed for my .NET 5 project, and whatever the default versions of those packages for the new .NET Core 3.1 project. Both projects fail to correctly scaffold the needed files.

Answer 1

I ran into this yesterday.

What I had to do was install version 3.1.13 of Microsoft.AspNetCore.ApiAuthorization.IdentityServer and then Microsoft.AspNetCore.Identity.UI and after that, the scaffolding worked in VS2019

All of my AspCoreNet packages were set to 3.1.15 previously.