“The name 'HTML' does not exist in the current context” in MVC 3 Views

Question

I´m starting to use \"MVC 3\" but I´m facing some little problems. In my Views, when I code something like this:

@if(Request.IsAuthenticated) {
    

        

Answer 1

Set the property of System.Web.MVC,Copy Local = True

Answer 2

What worked for me was closing Visual Studio, deleting the user option files (both solution and project level), then relaunching Visual Studio.

Answer 3

I'm using dotnet core sdk 2.2 and Visual Studio Professional 2019.

This was caused by Visual Studio mangling code.

Code was pasted into the razor view. Visual Studio would attempt but then fail to auto-format it. Part of the failure resulted in deleting code.

Pressing ctrl+z reverted the formatting but kept the pasted code. The razor compilation errors were then fixed (The name 'Html' does not exist in the current context)

Disable format on paste (see https://stackoverflow.com/a/28053865/1462295 ) under Tools -> Options -> Text Editor -> HTML -> Advanced