Error executing the selected code generator 'Object reference not set to an instance of an object'

### Description

When In try to add a new controller with scaffolding.

I have folloed all the instructions for two time and erevyting is like you put but allways say the same.

[Escriba sus comentarios aquí]

### Page URL

https://learn.microsoft.com/es-es/aspnet/core/tutorials/first-mvc-app/adding-model?view=aspnetcore-9.0&tabs=visual-studio

### Content source URL

https://github.com/dotnet/AspNetCore.Docs/blob/main/aspnetcore/tutorials/first-mvc-app/adding-model.md

### Document ID

48e81b42-7c2b-afbf-71e6-d4f442a4bd1f

### Platform Id

35671a1b-cf9f-0101-6b1b-84693f6a18f6

### Article author

@wadepickett

### Metadata

* ID: 1d975a83-1550-b284-d0d8-7fe2ea206ff5
* PlatformId: 35671a1b-cf9f-0101-6b1b-84693f6a18f6
* Service: **aspnet-core**
* Sub-service: **tutorials**

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