An unexpected error was detected while trying to resolve the tag helper directive '@addTagHelper'

Question

I am using the Visual Studio 2015 community version and I created an ASP.NET MVC 5 project.

When I open the view ( Index of Home or any other), it shows the first three lines of the page, underlined in red as a syntax problem. Here is the error:

An unexpected error was detected while trying to enable support for the @addTagHelper directive tag with the value "Microsoft.AspNet.Mvc.Razor.TagHelpers.UrlResolutionTagHelper, Microsoft.AspNet.Mvc.Razor". Error: the reference to the object is not installed in the instance of the object

Screenshot:

When I create a project, it is successfully built. When I run it, it shows a lot of errors, but it launches the application.

The type or namespace name 'Mvc' does not exist in the Microsoft.AspNet namespace (do you miss the assembly reference?)

and

'_ Page_views_home_index_cshtml.ExecuteAsync ()': no ​​suitable method found to override

How can I get rid of this?

Answer 1

Here is how I fixed the problem:

First, clear the Visual Studio component cache by closing Visual Studio and deleting this folder:

C: \ Users \ [Username] \ AppData \ Local \ Microsoft \ VisualStudio \ 14.0 \ ComponentModelCache

Finally, check the web.config files and change:

 <appSettings> <add key="webpages:Version" value="2.0.0.0" /> ... </appSettings> 

at

 <appSettings> <add key="webpages:Version" value="3.0.0.0" /> ... </appSettings> 

Answer 2

I had the same problem, but above it did not work. I also deleted all 4 files in the cache of components that did not work. I noticed that the line below <appSettings> was set to false . I changed it to true and the red squitts disappeared.

 <add key="webpages:Version" value="3.0.0.0" /> <add key="webpages:Enabled" value="false" /> 

Answer 3

In my case, it was a link to System.Web.Mvc.

There were a lot of errors in the cshtml files, but it compiled and worked. Then I found that I had an error in the xxxcontrollers.cs file when trying to inherit the controllers.

It seems that it can compile because the DLL was already in bin, but it threw errors.

I could not rebuild this project. These would be days and days.