Develop Reference

Issue in .net6 gRPC project template [duplicate]

I have a multi-project solution with Prism Nuget packages installed in several projects. I then attempted to add a Prism Mef extensions package to one of the projects using the Nuget Package Manager UI (I have already added it to one of the other projects).
The first time I attempted to add the package, it failed to install one of the dependencies, no specific error reason, just "failed". So, I installed it a second time, all seemed to be fine, no errors reported, but a few of the references did not resolve.
So, I uninstalled the package and all dependencies and installed it again. Again all appeared fine, but more references do not resolve.
I have tried uninstalling and installing the package more times but get the same result every time now.
I have had this problem many times and I know its not specific to the Prism package as I've had it with loads of different packages.
I think its just a major bug with Nuget, but I'm hoping somebody will know an easy way to fix it. I think I usually have better success with the Nuget console, but I find it more effort to use.
I've done some searching online and not really found a good explanation of the cause of the problem or a way to resolve it.
Somebody at work completely refuses to have anything to do with Nuget as he has so many of these issues, but I am determined to make it work!

Within the Package Manager Console run the following command:
Update-Package -reinstall
This will reinstall each nuget package within that project which should resolve any missing references.
If you know you're missing a specific reference:
Update-Package -reinstall <Package-Name>

I just closed Visual Studio and reopened it and references are resolved...!

You need to follow this procedure.
1. Update-Package -reinstall
2. Restart visual studio.

You may want to check the .NET version of the package vs. your project.
I had an instance where my project was .NET 4.6.1, and the package I was attempting to install was using version 4.6.2. After updating my project to the same .NET version, the reference showed up.

I recently encountered this error on visual studio 2012, solution for me was to delete .nupkg file from nuget cache. Nuget cache location can be found from nuget settings > general > browse.
Note: I did not clear cache, I just deleted a specific file from cache directory and reinstalled the nuget package.

Delete all the <assemblyBinding> references from your .config file, then run this command from the Nuget Package Manager:
Get-Project -All | Add-BindingRedirect

This is how I fixed it.
I was working on a legacy .NET framework project (using <Reference Include... rather than PackageReference). The .dlls were referenced with a relative path that wasn't being resolved.
Fixed by changing to absolute paths, building, then changing back to the original relative paths.
For example:
<Reference Include="My.Package">
<HintPath>..\..\packages\My.Package.dll</HintPath>
</Reference>
Changed to:
<Reference Include="My.Package">
<HintPath>C:\Users\will\Documents\MySolution\packages\My.Package.dll</HintPath>
</Reference>
Then built and changed back to the relative path and the build still worked.

In our case, on one machine VS was holding onto an old version of a dependency, so references to newly added methods in the dependency were not resolving (even when package manager was reporting the latest version installed). The solution was to restart visual after uninstalling the dependency, then install again.

GetPathsOfAllDirectoriesAbove() cannot be evaluated after updating .Net Framework version (4.6.2 to 4.7.2)

A project I have been working on was upgraded from .NET Framework 4.6.2 to 4.7.2.
On build, in a file that is not my code, I get the following error:
I also see the same error in the build tab of my project properties.
I'm at a loss- I've searched for the error and am coming up empty. Has anyone encountered and/or resolved this before?

Looks like after upgrading your build tool is changed from MSBUILD to Roslyn. Microsoft.Managed.Core.targets is Roslyn target file.
if you have following Nuget packages installed:
Microsoft.CodeDom.Providers.DotNetCompilerPlatform
Microsoft.Net.Compilers
Then possibly it's causing the issue. Upgrade the Microsoft.CodeDom.Providers.DotNetCompilerPlatform to 2.x and remove the second one. That should fix the issue.

Ran into the same error - a compatibility issue between Microsoft.Net.Compilers 2.x (vs2017) and 3.x (vs2019) - downgrading from v3 to v2 fixed the issue specifically on our build agents which only had VS2017. v3 requires VS 2019 or later per roslyn-analyzers release spec.
Per the related error Method 'System.String.GetPathsOfAllDirectoriesAbove' not found - VS2017 would not even open the CSPROJ which was a clue about compatibility.
VS 2017 - CSPROJ Option to Install Missing Features for Microsoft.Net.Compilers v3
VS 2017 - Installing Missing Features

This happned to me when I updated Microsoft.Net.Compilers in an old project.
Removing Microsoft.Net.Compilers completely, and then updating Microsoft.CodeDom.Providers.DotNetCompilerPlatform resolved my problem.

This can also happen when trying to compile a VS2019 project with an older version of Visual Studio (e.g., on a build server or in Azure DevOps).
If, after applying the solution from answer https://stackoverflow.com/a/59276492/2279059, the error changes to
##[error]CSC(0,0): Error CS1617: Invalid option '8.0' for /langversion
then this is likely the case. The solution is then to build with the right version of Visual Studio (2019).

This error usually comes when you upgrade the below libraries by nuget
Microsoft.CodeDom.Providers.DotNetCompilerPlatform
Microsoft.Net.Compilers
Guys, If your project is not loading due to this error. just go to that project location by explorer and delete the obj folder manually.
Then right-click on the project and RELOAD AGAIN.

Why is Referenced Component not be found in Visual Studio 2017 when it is found in Visual Studio 2015

I have a solution with two projects - a primary project, and a unit test project. When opening in Visual Studio 2015 all references are found and project builds successfully. When opening in Visual Studio 2017 several but not all NuGet package references are not found and compile fails. Some of the failed references are...
System.Data.Common
System.Net.Http
System.Net.Http.WebRequest
System.Security.Cryptography.Algorithms
System.Security.Cryptography.Encoding
System.Security.Cryptography.Primitives
System.Security.Cryptography.X509Certificates
... but other NuGet references are found with no problem. This solution was created with VS2015. When viewing the .csproj file nothing out of the ordinary is jumping out.
I am thinking of rebuilding it from scratch in VS2017 to try to identify the problem.
Has anyone else experienced this problem, and/or has anyone any suggestions on why this is occurring and what should be done to facilitate a fix?
Update:
I created a brand new VS2017 WebApi project referencing .NET 4.7.1, and compiled successfully. I then added NuGet package System.Data.Common 4.3.0. The NuGet install process appears to have completed with no errors, but still I am left with an invalid reference. That was pretty easy to replicate.

OK, answering my own question.
I found what I believe is the answer. This particular project was originally developed in VS2015 using .NET 4.6.2. When changing to VS2017 we elected to upgrade .NET to 4.7.1. The problem is with the .NET version, not the VS version.
The newer version of .NET has many of these NuGet assemblies added to standard libraries. The NuGet packages were in conflict with the native .NET 4.7.1 namespaces. For example, in .NET 4.7.1, the namespace System.Data.Common is found in the assembly System.Data.dll. No longer is it required to add a NuGet assembly System.Data.Common.dll. In fact, if I do add System.Data.Common NuGet package assembly, I now have two assemblies having the namespace System.Data.Common - one in System.Data.dll and another in System.Data.Common.dll - hence the reference problem.
The solution is to use the .NET 4.7.1 version and remove the extra NuGet assembly. This was also true for System.Security conflicts. The conflict with System.Net.Http was actually moved into a NuGet assembly called Microsoft.AspNet.WebApi.Client.
I hope all of this helps someone else...(uhhhgggg)....
BTW - it appears that when using VS2015 with .NET 4.7.1, these conflicts are suppressed and never display. This feels like a shortcoming of VS2015. Glad VS2017 shows them to reveal the true problem...

Check your packages.config file to make sure the Nuget packages are actually listed as dependencies for your project.
Also, open the solution in VS 2015 and double check the file path for the references in question. Make sure the DLLs are not referenced from a file path unique to Visual Studio 2015.

I had to create a new project and transfer all the necessary files from the old project to new project to fix this.

The "Microsoft.CodeAnalysis.BuildTasks.Csc" task could not be loaded from the assembly

I have a project that I have on TFS online. When Im trying to build the project, I get the following error:
Severity Code Description Project File Line
Error The "Microsoft.CodeAnalysis.BuildTasks.Csc" task could not be loaded from the assembly C:\Users\Bryan\Source\Workspaces\TestProject\ContosoUniversity\packages\Microsoft.Net.Compilers.1.0.0\build..\tools\Microsoft.Build.Tasks.CodeAnalysis.dll. Could not load file or assembly 'file:///C:\Users\Bryan\Source\Workspaces\TestProject\ContosoUniversity\packages\Microsoft.Net.Compilers.1.0.0\tools\Microsoft.Build.Tasks.CodeAnalysis.dll' or one of its dependencies. Could not find the file. Confirm that the declaration is correct, that the assembly and all its dependencies are available, and that the task contains a public class that implements Microsoft.Build.Framework.ITask. ContosoUniversity
Has this something to do with that Azure don't support ASP.NET 4.6?

Here was the fix for me. Using Nuget Package Manager, remove these two packages if referenced:
Microsoft.CodeDom.Providers.DotNetCompilerPlatform
Microsoft.Net.Compilers
After that, run a rebuild. This ensured that the build was not trying to use a specific build exe. Click here for the Diff against previous revision

No, it is not related to Azure Web Apps doesn't support ASP.NET 4.6. Actually, you get this error message because NuGet packages are checked into version control.
So, you need to remove folder TestProject\ContosoUniversity\packages from TFS and build again. See: BuildTasks.Csc task could not be loaded from the assembly?

I had the same problem sometime ago, to fix it:
make sure your packages are not under source control
Force restore all package, by deleting the package folder
restart your visual studio

In my case it got resolved by updating the below two Nuget packages to the latest version:
Microsoft.CodeDom.Providers.DotNetCompilerPlatform
Microsoft.Net.Compilers

Delete the packages folder or its contents, clean, rebuild solves the problem for me.

If you take a look at the file in reference it points you to a packages location. It turns out that NuGet packages is broken
To Resolve: you simply need to delete that packages folder (usually under project name \ project name \ packages.), then on build, Nuget will restore all the required packages.

I needed to update all my Nuget packages on my development box, then check the project in to TFS again.
For added peace of mind, I deleted the packages folder in the Team City build folder.

In case someone looks at this later on.
I was getting this issue only when building in DevOps.
But after manually deleting packages in my local build I started getting the same issue locally.
After removing the apparently missing NuGets using the NuGet manager the issue resolved it's self both locally and on azure.
Not sure what caused it but might save someone a headache in the future.
I was using .net 4.7.2

Where can I find System.Web.Helpers, System.Web.WebPages, and System.Web.Razor?

I am following this article on RazorGenerator and it say's that I must add references to:
System.Web.Helpers.dll
System.Web.WebPages.dll
System.Web.Razor.dll
The only one I can see when I do Add Reference is System.Web.Razor, but I don't know where the other ones are.

You will find these assemblies in the Extensions group under Assemblies in Visual Studio 2010, 2012 & 2013 (Reference Manager)

To sum up all of the options for VS 2017, WebHelpers was installed by installing MVC in previous versions of Visual Studio. If you're getting this error, you probably don't have the older versions of VS installed anymore.
So, installing the Microsoft.AspNet.MVC NuGet package will require Microsoft.AspNet.WebPages and Microsoft.AspNet.Razor, and the Microsoft.AspNet.WebPages includes System.Web.Helpers.dll.
If you've got direct references to System.Web.Mvc.dll and you don't want to use NuGet for MVC, you can get the Microsoft.AspNet.WebPages NuGet, or there are some other NuGet packages that only contain System.Web.Helpers.dll, like the microsoft-web-helpers or System-Web-Helpers.dllpackages.
There appear to be 2 versions of System.Web.Helpers.dll, one for .Net 4.0 and one for 4.5. Choosing the correct version of MVC or AspNet.WebPages will ensure you get the right one.

As for VS2017 I didn't find it in "extensions", there's a Nuget package called "microsoft-web-helpers" that seems to be equivalent to System.Web.Helpers.

I had the same problem , first I couldn't find those dlls in the list of .NET components . but later I figured it out that the solution is :
1- first I changed target framework from .NET framework 4 client profile to .NET framework 4.
2- then scroll down the list of .NET components , pass first list of system.web... , scroll down , and find the second list of system.web... at the bottom , they're there .
I hope this could help others

In VS 2010 just right click on project or on reference and click add reference.
On the popup window Select Assemblies - > Extensions -> System.Web.Helpers

Installing ASP.NET MVC3 from here should help.

On VS2017 I installed the NuGet package: Microsoft.AspNet.WebPages
That did the trick.

This particular NuGet package has a habit of losing its references in one of our projects. From time to time I will need to run the following command in the Package Manager Console to restore the references and everything is OK again
Update-Package Microsoft.AspNet.Webpages -reinstall

I had to install RazorGenerator.Templating to get it all to work. From the NuGet console, type:
Install-Package RazorGenerator.Templating

They should be under C:\Program Files\Microsoft ASP.Net (or C:\Program Files (x86)\Microsoft ASP.Net if you're on a 64-bit OS) in a subfolder for MVC3 or WebPages.

The issue is a missing or outdated version of MVC. I was running VS 2015Preview and could resolve the issue by installing the latest version of MVC via NuGet.
Just in case anyone is still coming across this one.

When you install this nuget package Microsoft.AspNet.WebPages they can be find in C:\Program Files (x86)\Microsoft Visual Studio\Shared\Packages\Microsoft.AspNet.WebPages.x.x.x\lib\net45