Develop Reference

CSharpAddImportCodeFixProvider encountered an error and has been disabled

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.
CSharpAddImportCodeFixProvider encountered an error and has been disabled
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?

I had the same issue on VS-2015 update 3.
I did was :
1) Closing visual studio
2) restarting as administrator

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

There may be multiple reasons why this error occurs. So this answer may not apply to all situations, though it seems that it only occurs when another project is referenced.
The error does not occur for all statements. In my case I had the following code:
private System.Threading.Timer Timer;
public void Start()
{
Timer.Change(0, 60000);
}
As soon as intellisense would open for Timer.Change( the error occurred. Please note that I had no parameters at that point. If valid parameters are present there will be no error.
I could solve the issue by updating the version of the framework. I found out that both projects targetted different frameworks, resp. 4.5.2 and 4.6.
As long as the framework versions are different the error occurs. As soon as both are equal (either 4.5.2 or 4.6) the error no longer shows.
I have tested this with VisualStudioVersion = 14.0.25420.1 (Visual Studio Community 2015).
-- update --
I've reported this as a bug to Microsoft. Including steps to reproduce.

I end up with this same error.
what i did was to manually go and find the nuget packet for System.Data.SqlClient, installed and then invoke it in the class i was working on, like:
using System.Data.SqlClient;
Dont know if this is some kind of bug, cause it happens on a new blank project i create using visual studio 2019 community
hope it helps someone

Had the same problem solved by installing the sqlClient package from nuget package manager
right-click on the project choose manage nuget packages.. and go to browse tab and search for System.Data.SqlClient and install it. that easy :)

Judging from the label you were given, "CSharpAddImportCodeFixProvider", I'd guess your problem was due to Visual Studio trying to identify and/or correct a missing "using" statement at the top of your C# source code file in which you made reference to a class that needed it. The Visual Studio components that usually deal with this type of problem are Intellisense, or third-party syntax highlighting/correction plugins like JetBrains' ReSharper.
On second thought, I'm not quite sure it's Intellisense's fault as opposed to the plugin ReSharper's. That's to be determined.
I did file a similar bug report with Microsoft. The error in my case seemed to be a result of the Intellisense not knowing how to deal with a logic error in my own code (see https://connect.microsoft.com/VisualStudio/feedback/details/3133049).
In my case, I had inadvertently placed code for a method outside its class definition, though inside its similarly named namespace. Visual Studio 2015 Update 3 complained,
'GenerateVariableCodeFixProvider' encountered an error and has been
disabled.
The fix was to move my method back into its corresponding class definition, but it definitely brought a Visual Studio bug up to the surface.
Specifically, Visual Studio Intellisense had seen the line of code,
Response.Write("I did something");
placed in a method that was declared outside a class definition (i.e., inside a namespace, but inadvertently not inside its class). The "'FeatureLabel' encountered an error and has been disabled" error was then displayed in a yellow bar across the top of my editor window and an "Enable" button and an "Enable and ignore future errors" button were displayed next to it.
I believe that Intellisense (or ReSharper?) tried to automatically deal with the situation and attempted to generate a variable for the keyword, "Response", but it tripped trying to do so--which in turn caused the error that was displayed.

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

WPF error : The name does not exist in the namespace

I'm getting this problem building a WPF project
The name does not exist in the namespace
Everything I’ve looked at says you should
Change the namespace and the project name, build, change them back
Change the build from 86 to 64, build, and back Tried removing the
reference and letting ReSharper re-instate the reference Tried
excluding the file, build, then include the file again
None of the above worked.
I have checked that each referenced class has only one instance of it throughout the whole solution – ruling out named duplicates
The references in question are all references within the one DLL – all namespaces within this dll so it’s not like there is a cross dll issue of any sort.
Your thoughts or suggestions at this point are appreciated.

I to assume that You have this error in XAML file.
I thing it is very common problem with WPF and Visual Studio 2015.For example I have this error when I use DevExpress dlls
My suggestions is to try this:
Restart Visual Studio - it is weird but frequently it works. I don't now way it works.
Use F5 and run the program instead of build them (F6). Sometimes when You compile app the error disappear and app runs. It is also weird, but in my case it works
This not resolve the problem but it helps exclude the problem with IDE

VS 2010: C# Project Cannot Open DLL

I'm having an issue building a project that references a DLL located in the project's bin folder, which up until yesterday was building and running without issue.
The error I'm getting is fatal error CS0009: Metadata file 'c:\MyProject\bin\myClient.dll' could not be opened -- 'Error importing module 'myClient.netmodule' of assembly 'c:\MyProject\bin\myClient.dll' -- The system cannot find the file specified.' Intellisense is similarly complaining that The type or namespace 'Api' does not exist in the namespace 'Client' since it can't find the DLL.
Let me know if you think this is a duplicate, but I've viewed several similar posts and the solutions did solve my problem. Here are some examples:
Visual Studio 2010 — are you missing a using directive or an assembly reference?
VS2010 - Getting “type or namespace name could not be found” but everything seems ok?
Stymied by ASP.NET Compilation Error CS0009
Metadata file '…\Release\project.dll' could not be found in Visual Studio
Visual Studio 2010: Metadata file “…/Debug/Graph.dll” could not be found
Metadata file … could not be found error when building projects
Specifically, I've tried the following solutions (and combinations of these):
Cleaned and rebuilt my project.
Made sure that the target framework is not a 'client profile' version of .NET
Verifyied that the dll has been added as a project reference
Removed and re-added the project reference
Verified that the project is showing the DLL in the References section in Visual Studio
Repaired .NET
Verified the location of the DLL (it is in the local project's bin folder as given by the error)
Tried other versions of .NET
Closed and restarted Visual Studio
Rebooted my machine
Verified there are no hidden characters surrounding the 'using' statement
Removed all code changes since the last working build
Verified the settings in Configuration manager, including that 'Build' is checked
The project calling the DLL is a small class library that resides in a solution with one other small project (a console application). The DLL is an external DLL that I've been using successfully for several weeks in this project/solution. The error arises regardless of whether I build the project from the solution or by itself.
Any ideas about what could be going on?

Have you included bin folder in your project accidentally? If yes that might cause the issue. You can't include bin folder in your project as the bin folder will be created by the VS. If you accidentally include bin folder in your project, the bin project will be set to Copy to output which when you compile, the file is deleted and copied to output by Visual Studio that trigger weird behavior that some file is missing.
Hopes this help

Well I'm not sure exactly what happened here, but here is what finally resolved the issue:
A good-old-fashioned delete every single file and rebuild the project from those files from scratch. I gave +1 to some of the responses because they were useful to consider, and because there was probably a messed-up reference some where as Jonathon Wood suggested.

The referenced project x does not exists

Hej All,
I upgraded my solutions of a project from vs2008 to vs2010.
But right now I have a weird problem. I reference a project in multiple solutions (3 solutions)
In 2 of those solutions the referencing goes wrong.
I am able to add the reference (project reference) but when I build I got the warning the referenced project x does not exists. And errors that I have to add an reference.
I already deleted and added the project again, same with the references but no result.
Does anybody have any idea?
Greetz,
Jonathan

I had the a similar problem and the other solutions didn't help. What worked for me was opening the project file in a text editor. There were duplicate references to a library, one as a project reference and one as a dll reference. I deleted both. Then I opened the solution in Visual Studio, and re-added the reference as a project reference. Only one reference got added and I stopped getting the warning.

Make sure your project is not using the ".NET Framework 4 Client Profile" as target framework, this is the most common source of these problems.
You can check this in the project properties under Target Framework.
From MSDN:
If you are targeting the .NET
Framework 4 Client Profile, you cannot
reference an assembly that is not in
the .NET Framework 4 Client Profile.
Instead you must target the .NET
Framework 4. For more information, see
Troubleshooting .NET Framework
Targeting Errors.

I was experiencing the very same issue although I was correctly referencing .NET 3.5 in all the projects migrated from VS 2008 to VS 2010 (all references to System assemblies were using a runtime version v2.0).
Weird however, the error only occured if my solution (and the projects in this solution's subfolders) were located in certain path... I could "solve" the problem by moving the projects or renaming the projects (only the project file, not the output binaries) ?!
Double clicking the reference in the project opened correctly the Object Browser where I could find all the artifacts defined in the referenced project !
I did start to delete everything from the project (classes, resources, references, etc...). At the end, I had only two projects (A referencing B) without any other references and with only one empty class in each. I still had the message "referenced project '..\B\B.csproj' does not exist.". Suddenly, trying to copy the source to another PC and next back into the original path on my machine (kind of black magic to solve the problem), I did get the message "Cannot copy. Resulting file name is too long".
Wierd² !!! I did delete every thing on my PC and did copy back again the sources from the other PC. It passed successfully ! I did recopy again back from the other PC (overwriting now the existing local copy) and again I got the message "Cannot copy. Resulting file name is too long". So the problem occurred only when overwriting existing files.
I found that the error occurred only if the existing file was "readonly". Removing the flag readonly solved this issue. However, this error was the sign of something possibly at the root cause of my initial issue: "referenced project '..\B\B.csproj' does not exist."
So, I decided to check if the project path length was the issue by renaming one of the folder but not changing the total length! The error still occurred (reference not found).
Next (I knwow, you already think I am crazy or stupid. But all those steps were validated by various colleagues), I did copy the solution in a new folder (with a longer path). Surprise, the error did not occurred anymore !!!
But moving the solution back to a folder with the same length (possibly another name) was reintroducing the error (after a "Clean" of the solution otherwise the meta in obj helped to solved the reference).
I was also able to reproduce this by renaming the project file B instead of a folder in the path. A longer or shorter project filename was solving this issue.
The length of the project filepath is "195" :
D:\TFS_Builds\5\XXXX 1.1\Release 1.11\Sources\Release 1.11\Exception Repository\XXXXXX.Framework.ExceptionHandling.Repository.ServiceHost\XXXXXX.Framework.ExceptionHandling.Repository.ServiceHost
Also, as I can be very creative when trying to identify the root cause of a problem, I did create the very same path on C:\ and put the solution in there... Same error occurred.
I never found (until now) the reason of this and have posted a question on MSDN :http://social.msdn.microsoft.com/Forums/en/msbuild/thread/f0eb6aed-5854-4678-9546-09c1a7705e30

Here is what fixed my problem:
I had a refference to a project named "Utilities.Proxy3.5", which would give me a the following warning:
"The referenced project
'..\..\Utilities.Proxy3.5\Utilities.Proxy3.5.csproj' does not exist."
Renaming the project folder and the project files to "Utilities.Proxy35" and re-adding the reference solved the problem. Note: I have only removed a dot between the numbers 3 and 5.
I hope this will help someone.

I had the same issue.
What solved it for me was that i opened each of the reference projects on its own first. VS asks for a permission to fix some of the files. Allow it to do so.
Then open the top project and it will work.
Apparently it was issues with the version of VS that created the original project.
Good luck

Check the lengths of the following:
The path of the referencing project's directory
The relative path to the project it references
If those paths add up to exactly 259 characters, you will experience a bug in the .NET implementation of Path.GetFullPath that will cause VisualStudio 2010 to behave as if the referenced project does not exist.

"An assembly with the same simple name has already been imported" error without duplicate reference

I'm getting the following error:
error CS1704: An assembly with the same simple name
'Interop.xxx.dll, Version=1.0.0.0, Culture=neutral,
PublicKeyToken=null has already been imported. Try removing one of the
references or sign them to enable side-by-side.
Everything I've seen says that I am referencing two assemblies with the same name and I need to remove one of them. However, I've checked and I'm only referencing it once.
This also only happens when I'm using msbuild to build from the command line on my dev box. If I build through Visual Studio or do a clean build on our CI server I don't see this error.
I've tried completely removing all of my source and building from scratch to more closely resemble the build machine but no luck.

So it looks like I can't read today!
The project had a reference to the Interop and a COM reference that generated the "same" interop. So there were two and I just didn't search very well. I still don't understand why it worked in other places but this did fix it.

In the Error List window, the project that was triggering this error was listed in the Project column. I got around the error by doing the following:
I unloaded the listed project (right-click => Unload Project)
Opened the XML for edit (right-click the unloaded project => Edit {ProjectName.csproj}).
Searched for the offending .dll, and noticed it was listed multiple times in the XML
Removed the entire Reference tag related to the offending dll, and did so for every copy of the reference except the first one listed
The reason it was listed multiple times was because several referenced libraries used that dll. This shouldn't be a problem, in and of itself, so I'm not sure what caused this error to suddenly pop up for me. I'll update this answer if I figure that out.

In my case the duplicate entry was caused by a NuGet package reference and a direct file reference to the same assembly in the packages folder. I am not sure how the project got into this state, but unloading the project and searching the XML file for the offending assembly name resolved the issue for me.
Note that in my case this started happening after updating a NuGet package to a newer version with no other changes to the project, so this maybe caused by a bug in NuGet.

If this is a web project, are there any strong-named references to the other version there? Those won't show up as a project dependency, but will cause a run-time error like you describe. Hope that helps

I had this problem but in my case, I had an old copy placed in the current folder for the EXE loading my component, that was loaded together with the current one, that was loaded by hand from my projects folder. Deleting that old copy solved my problem.
I used Debug > Windows > Modules window to see which modules were loaded at that time and that solved my problem.

For others facing the same as me: if building via command line using property AssemblyName, it will overwrite all assemblies generated by all solution projects - in other words, you will end up with (N -1) assemblies named the same where N is the no. of projects - the startup one (which generally will generate an exe).
This happens because all build command line properties are global and overwrite any project-specific setting. See this and this.
From the msdn link mentioned above:
Global properties are properties that are set by using the
/property switch on the command line, or properties that are set by
the integrated development environment (IDE) before a project is
built. These global properties are applied to all projects that are
built by using this Engine.
In my specific case, where Jenkins is the CI tool, I ended up adding a windows batch command at the end to rename the .exe only to what I originally intended when passing the AssemblyName parameter.

For those developing UWP projects that have project references that include specifically the Microsoft.Windows.SDK.Contracts nuget package (or other dependencies that reference it), this is a common error when the version of the SDK contracts is targeting a different version of the runtime to how your project is configured.
For instance, when targeting Windows 10, version 1903:
Any dependencies or reference projects should target or at least support the same runtime version.
it is common thought process to update all NuGet packages when a new stable version is available, but this is not always a helpful practise on its own. Just because a new stable version of a package is available does not mean that you should or that you can easily use that version.
Even though this package for SDK contracts has a stable update, it is not compatible with my main project configuration, Nuget does not know this so it allows the update.
This package is specifically designed to provide windows dlls for project types that DO NOT have windows platform targeting support, it copies the same dlls that are included by the UWP targeting config. By installing later versions of the package the references from the satellite project will be included in the output along with those provided due to platform targeting, ultimately causing OPs error.
There are similar SDK and targeting packs for Windows IoT Device Runtimes, this information should help you identify and resolve those issues if you get stuck on this issue as my team often does :)

In my case, the issue was on wrong characters in the ProjectReference section of my csproj file.
Background
I have a project that references another library I maintain, which I publish as a NuGet package.
Whenever I make changes to my library, I usually reference the local dll in my project to test and make sure everything looks good before I publish the library as a NuGet package.
When testing, I just comment out the PackageReference line and uncomment the ProjectReference one so it references my local dll, like so:
<ProjectReference Include="..\..\my-class-library\MyClassLibrary.csproj" />
<!--<PackageReference="MyClassLibrary" Version="2.0.1"/>-->
Root cause
I had the slashes inverted, so I was using / rather than \ in the path, like so:
<ProjectReference Include="../../my-class-library/MyClassLibrary.csproj" />
Once corrected, the issue went away.

Try this instead: remove Interop.xx.dll from the reference section in Solution Explorer and Rebuild the project

In our case this error was shown when we had a duplicate reference inside the .csproj file (although I have no idea how this happened).
The difference to an already posted answer is that, in our case, one was a project reference and another one was direct binary reference to a dll.
Once we removed one of those, project correctly compiled.