Question: I had my PC re-imaged for me. I have Visual Studio Version 14.0.25123.00 Update 2 installed on my computer. I'm getting this error when I try to use VS intellisense to reference another project. 

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> CSharpAddImportCodeFixProvider encountered an error and has been disabled
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I have two projects. One of them using namespace `ProjectName.Web`. And the other project using `ProjectName.Web.Controllers`. The provider crashes when I reference `ProjectName.Web.Controllers`, I believe because it is setup as a project. Any idea how to fix this?

Answer: 
Happened to me when chose `Add using System.Data.SqlClient` automatically after typing `using (SqlConnection...){}` in DataLayer, in one of Repository classes.

Nothing helped (except creating new project), but I saw that the problem was with loading `System.Data.SqlClient.dll` file, although it existed in appropriate folder.

Found by trial and error that after removing `Dependencies->Assemblies->System.Data.SqlClient` from DataLayer (right click -> Remove, or just press Delete key when selected), I can Add `System.Data.SqlClient` without any errors.

Didn't try for other cases where `CSharpAddImportCodeFixProvider encountered an error and has been disabled` message appears, but the solution might be similar.

In my case the problem appeared probably due to `.net` Core version conflict or something like that, because the project was on external drive and created on another computer.

Edit: Also, some errors might be caused by .vs folder (hidden by default) inside Solution folder, especially if the project is moved between different computers. I know from experience that IntelliSense can seem to be broken and classes from other namespace would be unavailable although `using namespace_name` statement is present. The solution is to delete .vs folder or just avoid copying it with the project, as suggested here: <https://weblog.west-wind.com/posts/2018/Aug/07/Fixing-Visual-Studio-Intellisense-Errors>
anyone trying this solution from here ? 

<https://developercommunity.visualstudio.com/content/problem/623872/add-import-not-working.html>

the last reply solves my issue..

`Tools` > `Options` > `Text Editor` > `C#` > `Advanced`

turning off `Suggest usings for types in NuGet packages`